Merge branch 'add-error-reason'

42 files changed, 1021 insertions, 621 deletions

diff --git a/src/adhoc.erl b/src/adhoc.erl
index 788bf65a..83a113a0 100644
--- a/src/adhoc.erl
+++ b/src/adhoc.erl
@@ -68,7 +68,9 @@ parse_request(#iq{type = set, lang = Lang, sub_el = SubEl, xmlns = ?NS_COMMANDS}
         xdata     = XData,
         others    = Others
     };
-parse_request(_) -> {error, ?ERR_BAD_REQUEST}.
+parse_request(#iq{lang = Lang}) ->
+    Text = <<"Failed to parse ad-hoc command request">>,
+    {error, ?ERRT_BAD_REQUEST(Lang, Text)}.
 
 %% Borrowed from mod_vcard.erl
 find_xdata_el(#xmlel{children = SubEls}) ->
diff --git a/src/ejabberd_c2s.erl b/src/ejabberd_c2s.erl
index 936abc7a..3736f7d0 100644
--- a/src/ejabberd_c2s.erl
+++ b/src/ejabberd_c2s.erl
@@ -619,8 +619,9 @@ wait_for_auth({xmlstreamelement, El}, StateData) ->
 	    send_element(StateData, Res),
 	    fsm_next_state(wait_for_auth, StateData);
 	{auth, _ID, set, {_U, _P, _D, <<"">>}} ->
-	    Err = jlib:make_error_reply(El,
-		    ?ERR_AUTH_NO_RESOURCE_PROVIDED((StateData#state.lang))),
+	    Lang = StateData#state.lang,
+	    Txt = <<"No resource provided">>,
+	    Err = jlib:make_error_reply(El, ?ERRT_NOT_ACCEPTABLE(Lang, Txt)),
 	    send_element(StateData, Err),
 	    fsm_next_state(wait_for_auth, StateData);
 	{auth, _ID, set, {U, P, D, R}} ->
@@ -685,7 +686,10 @@ wait_for_auth({xmlstreamelement, El}, StateData) ->
 			    ejabberd_hooks:run(c2s_auth_result, StateData#state.server,
 				[false, U, StateData#state.server,
 				    StateData#state.ip]),
-			    Err = jlib:make_error_reply(El, ?ERR_NOT_AUTHORIZED),
+			    Lang = StateData#state.lang,
+			    Txt = <<"Legacy authentication failed">>,
+			    Err = jlib:make_error_reply(
+				    El, ?ERRT_NOT_AUTHORIZED(Lang, Txt)),
 			    send_element(StateData, Err),
 			    fsm_next_state(wait_for_auth, StateData)
 		    end;
@@ -706,7 +710,9 @@ wait_for_auth({xmlstreamelement, El}, StateData) ->
 			    ejabberd_hooks:run(c2s_auth_result, StateData#state.server,
 				[false, U, StateData#state.server,
 				    StateData#state.ip]),
-			    Err = jlib:make_error_reply(El, ?ERR_NOT_ALLOWED),
+			    Lang = StateData#state.lang,
+			    Txt = <<"Legacy authentication forbidden">>,
+			    Err = jlib:make_error_reply(El, ?ERRT_NOT_ALLOWED(Lang, Txt)),
 			    send_element(StateData, Err),
 			    fsm_next_state(wait_for_auth, StateData)
 		    end
@@ -1013,7 +1019,7 @@ wait_for_bind({xmlstreamelement, #xmlel{name = Name, attrs = Attrs} = El},
     end;
 wait_for_bind({xmlstreamelement, El}, StateData) ->
     case jlib:iq_query_info(El) of
-      #iq{type = set, xmlns = ?NS_BIND, sub_el = SubEl} =
+      #iq{type = set, lang = Lang, xmlns = ?NS_BIND, sub_el = SubEl} =
 	  IQ ->
 	  U = StateData#state.user,
 	  R1 = fxml:get_path_s(SubEl,
@@ -1025,7 +1031,8 @@ wait_for_bind({xmlstreamelement, El}, StateData) ->
 	      end,
 	  case R of
 	    error ->
-		Err = jlib:make_error_reply(El, ?ERR_BAD_REQUEST),
+		Txt = <<"Malformed resource">>,
+		Err = jlib:make_error_reply(El, ?ERRT_BAD_REQUEST(Lang, Txt)),
 		send_element(StateData, Err),
 		fsm_next_state(wait_for_bind, StateData);
 	    _ ->
@@ -1099,6 +1106,7 @@ open_session(StateData) ->
     U = StateData#state.user,
     R = StateData#state.resource,
     JID = StateData#state.jid,
+    Lang = StateData#state.lang,
     case acl:match_rule(StateData#state.server,
                         StateData#state.access, JID) of
         allow ->
@@ -1136,7 +1144,8 @@ open_session(StateData) ->
                                StateData#state.server, [JID]),
             ?INFO_MSG("(~w) Forbidden session for ~s",
                       [StateData#state.socket, jid:to_string(JID)]),
-            {error, ?ERR_NOT_ALLOWED}
+	    Txt = <<"Denied by ACL">>,
+            {error, ?ERRT_NOT_ALLOWED(Lang, Txt)}
     end.
 
 session_established({xmlstreamelement, #xmlel{name = Name} = El}, StateData)
@@ -2275,30 +2284,32 @@ get_priority_from_presence(PresencePacket) ->
     end.
 
 process_privacy_iq(From, To,
-		   #iq{type = Type, sub_el = SubEl} = IQ, StateData) ->
-    {Res, NewStateData} = case Type of
-			    get ->
-				R = ejabberd_hooks:run_fold(privacy_iq_get,
-							    StateData#state.server,
-							    {error,
-							     ?ERR_FEATURE_NOT_IMPLEMENTED},
-							    [From, To, IQ,
-							     StateData#state.privacy_list]),
-				{R, StateData};
-			    set ->
-				case ejabberd_hooks:run_fold(privacy_iq_set,
-							     StateData#state.server,
-							     {error,
-							      ?ERR_FEATURE_NOT_IMPLEMENTED},
-							     [From, To, IQ])
-				    of
-				  {result, R, NewPrivList} ->
-				      {{result, R},
-				       StateData#state{privacy_list =
-							   NewPrivList}};
-				  R -> {R, StateData}
-				end
-			  end,
+		   #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ, StateData) ->
+    Txt = <<"No module is handling this query">>,
+    {Res, NewStateData} =
+	case Type of
+	    get ->
+		R = ejabberd_hooks:run_fold(
+		      privacy_iq_get,
+		      StateData#state.server,
+		      {error, ?ERRT_FEATURE_NOT_IMPLEMENTED(Lang, Txt)},
+		      [From, To, IQ,
+		       StateData#state.privacy_list]),
+		{R, StateData};
+	    set ->
+		case ejabberd_hooks:run_fold(
+		       privacy_iq_set,
+		       StateData#state.server,
+		       {error, ?ERRT_FEATURE_NOT_IMPLEMENTED(Lang, Txt)},
+		       [From, To, IQ])
+		of
+		    {result, R, NewPrivList} ->
+			{{result, R},
+			 StateData#state{privacy_list =
+					     NewPrivList}};
+		    R -> {R, StateData}
+		end
+	end,
     IQRes = case Res of
 	      {result, Result} ->
 		  IQ#iq{type = result, sub_el = Result};
@@ -2365,15 +2376,16 @@ process_unauthenticated_stanza(StateData, El) ->
 	      _ -> El
 	    end,
     case jlib:iq_query_info(NewEl) of
-      #iq{} = IQ ->
+      #iq{lang = L} = IQ ->
 	  Res = ejabberd_hooks:run_fold(c2s_unauthenticated_iq,
 					StateData#state.server, empty,
 					[StateData#state.server, IQ,
 					 StateData#state.ip]),
 	  case Res of
 	    empty ->
+		Txt = <<"Authentication required">>,
 		ResIQ = IQ#iq{type = error,
-			      sub_el = [?ERR_SERVICE_UNAVAILABLE]},
+			      sub_el = [?ERRT_SERVICE_UNAVAILABLE(L, Txt)]},
 		Res1 = jlib:replace_from_to(jid:make(<<"">>,
 							  StateData#state.server,
 							  <<"">>),
@@ -2879,6 +2891,7 @@ handle_unacked_stanzas(StateData)
 		    false
 	      end
 	end,
+    Lang = StateData#state.lang,
     ReRoute = case ResendOnTimeout of
 		true ->
 		    fun(From, To, El, Time) ->
@@ -2887,9 +2900,11 @@ handle_unacked_stanzas(StateData)
 		    end;
 		false ->
 		    fun(From, To, El, _Time) ->
+			    Txt = <<"User session not found">>,
 			    Err =
-				jlib:make_error_reply(El,
-						      ?ERR_SERVICE_UNAVAILABLE),
+				jlib:make_error_reply(
+				  El,
+				  ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)),
 			    ejabberd_router:route(To, From, Err)
 		    end
 	      end,
@@ -2897,7 +2912,9 @@ handle_unacked_stanzas(StateData)
 		?DEBUG("Dropping presence stanza from ~s",
 		       [jid:to_string(From)]);
 	   (From, To, #xmlel{name = <<"iq">>} = El, _Time) ->
-		Err = jlib:make_error_reply(El, ?ERR_SERVICE_UNAVAILABLE),
+		Txt = <<"User session not found">>,
+		Err = jlib:make_error_reply(
+			El, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)),
 		ejabberd_router:route(To, From, Err);
 	   (From, To, El, Time) ->
 		%% We'll drop the stanza if it was <forwarded/> by some
diff --git a/src/ejabberd_local.erl b/src/ejabberd_local.erl
index 7c30f3b6..5566073e 100644
--- a/src/ejabberd_local.erl
+++ b/src/ejabberd_local.erl
@@ -74,7 +74,7 @@ start_link() ->
 process_iq(From, To, Packet) ->
     IQ = jlib:iq_query_info(Packet),
     case IQ of
-      #iq{xmlns = XMLNS} ->
+      #iq{xmlns = XMLNS, lang = Lang} ->
 	  Host = To#jid.lserver,
 	  case ets:lookup(?IQTABLE, {XMLNS, Host}) of
 	    [{_, Module, Function}] ->
@@ -87,8 +87,10 @@ process_iq(From, To, Packet) ->
 		gen_iq_handler:handle(Host, Module, Function, Opts,
 				      From, To, IQ);
 	    [] ->
-		Err = jlib:make_error_reply(Packet,
-					    ?ERR_FEATURE_NOT_IMPLEMENTED),
+		Txt = <<"No module is handling this query">>,
+		Err = jlib:make_error_reply(
+			Packet,
+			?ERRT_FEATURE_NOT_IMPLEMENTED(Lang, Txt)),
 		ejabberd_router:route(To, From, Err)
 	  end;
       reply ->
@@ -166,8 +168,10 @@ refresh_iq_handlers() ->
     ejabberd_local ! refresh_iq_handlers.
 
 bounce_resource_packet(From, To, Packet) ->
+    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+    Txt = <<"No available resource found">>,
     Err = jlib:make_error_reply(Packet,
-				?ERR_ITEM_NOT_FOUND),
+				?ERRT_ITEM_NOT_FOUND(Lang, Txt)),
     ejabberd_router:route(To, From, Err),
     stop.
 
diff --git a/src/ejabberd_s2s.erl b/src/ejabberd_s2s.erl
index 0eab4633..be1ee465 100644
--- a/src/ejabberd_s2s.erl
+++ b/src/ejabberd_s2s.erl
@@ -312,8 +312,10 @@ do_route(From, To, Packet) ->
 	    <<"error">> -> ok;
 	    <<"result">> -> ok;
 	    _ ->
-		Err = jlib:make_error_reply(Packet,
-					    ?ERR_SERVICE_UNAVAILABLE),
+		Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+		Txt = <<"No s2s connection found">>,
+		Err = jlib:make_error_reply(
+			Packet, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)),
 		ejabberd_router:route(To, From, Err)
 	  end,
 	  false
diff --git a/src/ejabberd_service.erl b/src/ejabberd_service.erl
index 5caae610..465fb587 100644
--- a/src/ejabberd_service.erl
+++ b/src/ejabberd_service.erl
@@ -280,7 +280,9 @@ stream_established({xmlstreamelement, El}, StateData) ->
 	 and (FromJID /= error) ->
 	   ejabberd_router:route(FromJID, ToJID, NewEl);
        true ->
-	   Err = jlib:make_error_reply(NewEl, ?ERR_BAD_REQUEST),
+	   Lang = fxml:get_tag_attr_s(<<"xml:lang">>, El),
+	   Txt = <<"Incorrect stanza name or from/to JID">>,
+	   Err = jlib:make_error_reply(NewEl, ?ERRT_BAD_REQUEST(Lang, Txt)),
 	   send_element(StateData, Err),
 	   error
     end,
@@ -360,7 +362,9 @@ handle_info({route, From, To, Packet}, StateName,
 					      attrs = Attrs2, children = Els}),
 	  send_text(StateData, Text);
       deny ->
-	  Err = jlib:make_error_reply(Packet, ?ERR_NOT_ALLOWED),
+	  Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	  Txt = <<"Denied by ACL">>,
+	  Err = jlib:make_error_reply(Packet, ?ERRT_NOT_ALLOWED(Lang, Txt)),
 	  ejabberd_router:route_error(To, From, Err, Packet)
     end,
     {next_state, StateName, StateData};
diff --git a/src/ejabberd_sm.erl b/src/ejabberd_sm.erl
index 218e657f..4f7cfeea 100644
--- a/src/ejabberd_sm.erl
+++ b/src/ejabberd_sm.erl
@@ -159,8 +159,10 @@ check_in_subscription(Acc, User, Server, _JID, _Type, _Reason) ->
 -spec bounce_offline_message(jid(), jid(), xmlel()) -> stop.
 
 bounce_offline_message(From, To, Packet) ->
-    Err = jlib:make_error_reply(Packet,
-				?ERR_SERVICE_UNAVAILABLE),
+    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+    Txt = <<"User session not found">>,
+    Err = jlib:make_error_reply(
+	    Packet, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)),
     ejabberd_router:route(To, From, Err),
     stop.
 
@@ -423,6 +425,7 @@ do_route(From, To, #xmlel{} = Packet) ->
     #jid{user = User, server = Server,
 	 luser = LUser, lserver = LServer, lresource = LResource} = To,
     #xmlel{name = Name, attrs = Attrs} = Packet,
+    Lang = fxml:get_attr_s(<<"xml:lang">>, Attrs),
     case LResource of
       <<"">> ->
 	  case Name of
@@ -496,8 +499,9 @@ do_route(From, To, #xmlel{} = Packet) ->
 		  <<"headline">> -> route_message(From, To, Packet, headline);
 		  <<"error">> -> ok;
 		  <<"groupchat">> ->
-		      Err = jlib:make_error_reply(Packet,
-						  ?ERR_SERVICE_UNAVAILABLE),
+		      ErrTxt = <<"Incorrect message type">>,
+		      Err = jlib:make_error_reply(
+			      Packet, ?ERRT_SERVICE_UNAVAILABLE(Lang, ErrTxt)),
 		      ejabberd_router:route(To, From, Err);
 		  _ ->
 		      route_message(From, To, Packet, normal)
@@ -517,8 +521,10 @@ do_route(From, To, #xmlel{} = Packet) ->
 			<<"">> -> route_message(From, To, Packet, normal);
 			<<"error">> -> ok;
 			_ ->
-			    Err = jlib:make_error_reply(Packet,
-							?ERR_SERVICE_UNAVAILABLE),
+			    ErrTxt = <<"Incorrect message type">>,
+			    Err = jlib:make_error_reply(
+				    Packet,
+				    ?ERRT_SERVICE_UNAVAILABLE(Lang, ErrTxt)),
 			    ejabberd_router:route(To, From, Err)
 		      end;
 		  <<"iq">> ->
@@ -526,8 +532,10 @@ do_route(From, To, #xmlel{} = Packet) ->
 			<<"error">> -> ok;
 			<<"result">> -> ok;
 			_ ->
-			    Err = jlib:make_error_reply(Packet,
-							?ERR_SERVICE_UNAVAILABLE),
+			    ErrTxt = <<"User session not found">>,
+			    Err = jlib:make_error_reply(
+				    Packet,
+				    ?ERRT_SERVICE_UNAVAILABLE(Lang, ErrTxt)),
 			    ejabberd_router:route(To, From, Err)
 		      end;
 		  _ -> ?DEBUG("packet dropped~n", [])
@@ -684,7 +692,7 @@ get_max_user_sessions(LUser, Host) ->
 process_iq(From, To, Packet) ->
     IQ = jlib:iq_query_info(Packet),
     case IQ of
-      #iq{xmlns = XMLNS} ->
+      #iq{xmlns = XMLNS, lang = Lang} ->
 	  Host = To#jid.lserver,
 	  case ets:lookup(sm_iqtable, {XMLNS, Host}) of
 	    [{_, Module, Function}] ->
@@ -697,8 +705,10 @@ process_iq(From, To, Packet) ->
 		gen_iq_handler:handle(Host, Module, Function, Opts,
 				      From, To, IQ);
 	    [] ->
-		Err = jlib:make_error_reply(Packet,
-					    ?ERR_SERVICE_UNAVAILABLE),
+		Txt = <<"No module is handling this query">>,
+		Err = jlib:make_error_reply(
+			Packet,
+			?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)),
 		ejabberd_router:route(To, From, Err)
 	  end;
       reply -> ok;
diff --git a/src/mod_adhoc.erl b/src/mod_adhoc.erl
index 9947c84a..9e0682f7 100644
--- a/src/mod_adhoc.erl
+++ b/src/mod_adhoc.erl
@@ -233,7 +233,7 @@ process_sm_iq(From, To, IQ) ->
     process_adhoc_request(From, To, IQ, adhoc_sm_commands).
 
 process_adhoc_request(From, To,
-		      #iq{sub_el = SubEl} = IQ, Hook) ->
+		      #iq{sub_el = SubEl, lang = Lang} = IQ, Hook) ->
     ?DEBUG("About to parse ~p...", [IQ]),
     case adhoc:parse_request(IQ) of
       {error, Error} ->
@@ -245,8 +245,9 @@ process_adhoc_request(From, To,
 	      of
 	    ignore -> ignore;
 	    empty ->
+		Txt = <<"No hook has processed this command">>,
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_ITEM_NOT_FOUND]};
+		      sub_el = [SubEl, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)]};
 	    {error, Error} ->
 		IQ#iq{type = error, sub_el = [SubEl, Error]};
 	    Command -> IQ#iq{type = result, sub_el = [Command]}
@@ -277,7 +278,9 @@ ping_command(_Acc, _From, _To,
 						      [{<<"info">>,
 							translate:translate(Lang,
 									    <<"Pong">>)}]});
-       true -> {error, ?ERR_BAD_REQUEST}
+       true ->
+	    Txt = <<"Incorrect value of 'action' attribute">>,
+	    {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
     end;
 ping_command(Acc, _From, _To, _Request) -> Acc.
 
diff --git a/src/mod_announce.erl b/src/mod_announce.erl
index d30cf57f..0cf8c534 100644
--- a/src/mod_announce.erl
+++ b/src/mod_announce.erl
@@ -211,15 +211,15 @@ disco_identity(Acc, _From, _To, Node, Lang) ->
 
 %%-------------------------------------------------------------------------
 
--define(INFO_RESULT(Allow, Feats),
+-define(INFO_RESULT(Allow, Feats, Lang),
 	case Allow of
 	    deny ->
-		{error, ?ERR_FORBIDDEN};
+		{error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
 	    allow ->
 		{result, Feats}
 	end).
 
-disco_features(Acc, From, #jid{lserver = LServer} = _To, <<"announce">>, _Lang) ->
+disco_features(Acc, From, #jid{lserver = LServer} = _To, <<"announce">>, Lang) ->
     case gen_mod:is_loaded(LServer, mod_adhoc) of
 	false ->
 	    Acc;
@@ -229,13 +229,14 @@ disco_features(Acc, From, #jid{lserver = LServer} = _To, <<"announce">>, _Lang)
 	    case {acl:match_rule(LServer, Access1, From),
 		  acl:match_rule(global, Access2, From)} of
 		{deny, deny} ->
-		    {error, ?ERR_FORBIDDEN};
+		    Txt = <<"Denied by ACL">>,
+		    {error, ?ERRT_FORBIDDEN(Lang, Txt)};
 		_ ->
 		    {result, []}
 	    end
     end;
 
-disco_features(Acc, From, #jid{lserver = LServer} = _To, Node, _Lang) ->
+disco_features(Acc, From, #jid{lserver = LServer} = _To, Node, Lang) ->
     case gen_mod:is_loaded(LServer, mod_adhoc) of
 	false ->
 	    Acc;
@@ -246,25 +247,25 @@ disco_features(Acc, From, #jid{lserver = LServer} = _To, Node, _Lang) ->
 	    AllowGlobal = acl:match_rule(global, AccessGlobal, From),
 	    case Node of
 		?NS_ADMIN_ANNOUNCE ->
-		    ?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		    ?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_ANNOUNCE_ALL ->
-		    ?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		    ?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_SET_MOTD ->
-		    ?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		    ?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_EDIT_MOTD ->
-		    ?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		    ?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_DELETE_MOTD ->
-		    ?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		    ?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_ANNOUNCE_ALLHOSTS ->
-		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS]);
+		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_ANNOUNCE_ALL_ALLHOSTS ->
-		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS]);
+		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_SET_MOTD_ALLHOSTS ->
-		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS]);
+		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_EDIT_MOTD_ALLHOSTS ->
-		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS]);
+		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS], Lang);
 		?NS_ADMIN_DELETE_MOTD_ALLHOSTS ->
-		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS]);
+		    ?INFO_RESULT(AllowGlobal, [?NS_COMMANDS], Lang);
 		_ ->
 		    Acc
 	    end
@@ -283,10 +284,10 @@ disco_features(Acc, From, #jid{lserver = LServer} = _To, Node, _Lang) ->
     }
 )).
 
--define(ITEMS_RESULT(Allow, Items),
+-define(ITEMS_RESULT(Allow, Items, Lang),
 	case Allow of
 	    deny ->
-		{error, ?ERR_FORBIDDEN};
+		{error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
 	    allow ->
 		{result, Items}
 	end).
@@ -320,7 +321,7 @@ disco_items(Acc, From, #jid{lserver = LServer} = To, <<"announce">>, Lang) ->
 	    announce_items(Acc, From, To, Lang)
     end;
 
-disco_items(Acc, From, #jid{lserver = LServer} = _To, Node, _Lang) ->
+disco_items(Acc, From, #jid{lserver = LServer} = _To, Node, Lang) ->
     case gen_mod:is_loaded(LServer, mod_adhoc) of
 	false ->
 	    Acc;
@@ -331,25 +332,25 @@ disco_items(Acc, From, #jid{lserver = LServer} = _To, Node, _Lang) ->
 	    AllowGlobal = acl:match_rule(global, AccessGlobal, From),
 	    case Node of
 		?NS_ADMIN_ANNOUNCE ->
-		    ?ITEMS_RESULT(Allow, []);
+		    ?ITEMS_RESULT(Allow, [], Lang);
 		?NS_ADMIN_ANNOUNCE_ALL ->
-		    ?ITEMS_RESULT(Allow, []);
+		    ?ITEMS_RESULT(Allow, [], Lang);
 		?NS_ADMIN_SET_MOTD ->
-		    ?ITEMS_RESULT(Allow, []);
+		    ?ITEMS_RESULT(Allow, [], Lang);
 		?NS_ADMIN_EDIT_MOTD ->
-		    ?ITEMS_RESULT(Allow, []);
+		    ?ITEMS_RESULT(Allow, [], Lang);
 		?NS_ADMIN_DELETE_MOTD ->
-		    ?ITEMS_RESULT(Allow, []);
+		    ?ITEMS_RESULT(Allow, [], Lang);
 		?NS_ADMIN_ANNOUNCE_ALLHOSTS ->
-		    ?ITEMS_RESULT(AllowGlobal, []);
+		    ?ITEMS_RESULT(AllowGlobal, [], Lang);
 		?NS_ADMIN_ANNOUNCE_ALL_ALLHOSTS ->
-		    ?ITEMS_RESULT(AllowGlobal, []);
+		    ?ITEMS_RESULT(AllowGlobal, [], Lang);
 		?NS_ADMIN_SET_MOTD_ALLHOSTS ->
-		    ?ITEMS_RESULT(AllowGlobal, []);
+		    ?ITEMS_RESULT(AllowGlobal, [], Lang);
 		?NS_ADMIN_EDIT_MOTD_ALLHOSTS ->
-		    ?ITEMS_RESULT(AllowGlobal, []);
+		    ?ITEMS_RESULT(AllowGlobal, [], Lang);
 		?NS_ADMIN_DELETE_MOTD_ALLHOSTS ->
-		    ?ITEMS_RESULT(AllowGlobal, []);
+		    ?ITEMS_RESULT(AllowGlobal, [], Lang);
 		_ ->
 		    Acc
 	    end
@@ -396,7 +397,8 @@ announce_items(Acc, From, #jid{lserver = LServer, server = Server} = _To, Lang)
 commands_result(Allow, From, To, Request) ->
     case Allow of
 	deny ->
-	    {error, ?ERR_FORBIDDEN};
+	    Lang = Request#adhoc_request.lang,
+	    {error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
 	allow ->
 	    announce_commands(From, To, Request)
     end.
@@ -463,12 +465,13 @@ announce_commands(From, To,
 	    %% User returns form.
 	    case jlib:parse_xdata_submit(XData) of
 		invalid ->
-		    {error, ?ERR_BAD_REQUEST};
+		    {error, ?ERRT_BAD_REQUEST(Lang, <<"Incorrect data form">>)};
 		Fields ->
 		    handle_adhoc_form(From, To, Request, Fields)
 	    end;
        true ->
-	    {error, ?ERR_BAD_REQUEST}
+	    Txt = <<"Incorrect action or data form">>,
+	    {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
     end.
 
 -define(VVALUE(Val),
@@ -688,7 +691,9 @@ announce_all(From, To, Packet) ->
     Access = get_access(Host),
     case acl:match_rule(Host, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    Local = jid:make(<<>>, To#jid.server, <<>>),
@@ -703,7 +708,9 @@ announce_all_hosts_all(From, To, Packet) ->
     Access = get_access(global),
     case acl:match_rule(global, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    Local = jid:make(<<>>, To#jid.server, <<>>),
@@ -719,7 +726,9 @@ announce_online(From, To, Packet) ->
     Access = get_access(Host),
     case acl:match_rule(Host, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    announce_online1(ejabberd_sm:get_vh_session_list(Host),
@@ -731,7 +740,9 @@ announce_all_hosts_online(From, To, Packet) ->
     Access = get_access(global),
     case acl:match_rule(global, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    announce_online1(ejabberd_sm:dirty_get_sessions_list(),
@@ -752,7 +763,9 @@ announce_motd(From, To, Packet) ->
     Access = get_access(Host),
     case acl:match_rule(Host, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    announce_motd(Host, Packet)
@@ -762,7 +775,9 @@ announce_all_hosts_motd(From, To, Packet) ->
     Access = get_access(global),
     case acl:match_rule(global, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    Hosts = ?MYHOSTS,
@@ -815,7 +830,9 @@ announce_motd_update(From, To, Packet) ->
     Access = get_access(Host),
     case acl:match_rule(Host, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    announce_motd_update(Host, Packet)
@@ -825,7 +842,9 @@ announce_all_hosts_motd_update(From, To, Packet) ->
     Access = get_access(global),
     case acl:match_rule(global, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    Hosts = ?MYHOSTS,
@@ -861,7 +880,9 @@ announce_motd_delete(From, To, Packet) ->
     Access = get_access(Host),
     case acl:match_rule(Host, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    announce_motd_delete(Host)
@@ -871,7 +892,9 @@ announce_all_hosts_motd_delete(From, To, Packet) ->
     Access = get_access(global),
     case acl:match_rule(global, Access, From) of
 	deny ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_FORBIDDEN),
+	    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+	    Txt = <<"Denied by ACL">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_FORBIDDEN(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err);
 	allow ->
 	    Hosts = ?MYHOSTS,
diff --git a/src/mod_blocking.erl b/src/mod_blocking.erl
index 815884ff..d94b3090 100644
--- a/src/mod_blocking.erl
+++ b/src/mod_blocking.erl
@@ -64,29 +64,33 @@ process_iq(_From, _To, IQ) ->
     IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]}.
 
 process_iq_get(_, From, _To,
-	       #iq{xmlns = ?NS_BLOCKING,
+	       #iq{xmlns = ?NS_BLOCKING, lang = Lang,
 		   sub_el = #xmlel{name = <<"blocklist">>}},
 	       _) ->
     #jid{luser = LUser, lserver = LServer} = From,
-    {stop, process_blocklist_get(LUser, LServer)};
+    {stop, process_blocklist_get(LUser, LServer, Lang)};
 process_iq_get(Acc, _, _, _, _) -> Acc.
 
 process_iq_set(_, From, _To,
-	       #iq{xmlns = ?NS_BLOCKING,
+	       #iq{xmlns = ?NS_BLOCKING, lang = Lang,
 		   sub_el =
 		       #xmlel{name = SubElName, children = SubEls}}) ->
     #jid{luser = LUser, lserver = LServer} = From,
     Res = case {SubElName, fxml:remove_cdata(SubEls)} of
-	    {<<"block">>, []} -> {error, ?ERR_BAD_REQUEST};
+	    {<<"block">>, []} ->
+		Txt = <<"No items found in this query">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 	    {<<"block">>, Els} ->
 		JIDs = parse_blocklist_items(Els, []),
-		process_blocklist_block(LUser, LServer, JIDs);
+		process_blocklist_block(LUser, LServer, JIDs, Lang);
 	    {<<"unblock">>, []} ->
-		process_blocklist_unblock_all(LUser, LServer);
+		process_blocklist_unblock_all(LUser, LServer, Lang);
 	    {<<"unblock">>, Els} ->
 		JIDs = parse_blocklist_items(Els, []),
-		process_blocklist_unblock(LUser, LServer, JIDs);
-	    _ -> {error, ?ERR_BAD_REQUEST}
+		process_blocklist_unblock(LUser, LServer, JIDs, Lang);
+	    _ ->
+		Txt = <<"Unknown blocking command">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end,
     {stop, Res};
 process_iq_set(Acc, _, _, _) -> Acc.
@@ -125,7 +129,7 @@ parse_blocklist_items([#xmlel{name = <<"item">>,
 parse_blocklist_items([_ | Els], JIDs) ->
     parse_blocklist_items(Els, JIDs).
 
-process_blocklist_block(LUser, LServer, JIDs) ->
+process_blocklist_block(LUser, LServer, JIDs, Lang) ->
     Filter = fun (List) ->
 		     AlreadyBlocked = list_to_blocklist_jids(List, []),
 		     lists:foldr(fun (JID, List1) ->
@@ -143,8 +147,8 @@ process_blocklist_block(LUser, LServer, JIDs) ->
 				 end,
 				 List, JIDs)
 	     end,
-    case process_blocklist_block(LUser, LServer, Filter,
-				 gen_mod:db_type(LServer, mod_privacy))
+    case process_blocklist_block_db(LUser, LServer, Filter,
+				    gen_mod:db_type(LServer, mod_privacy))
 	of
       {atomic, {ok, Default, List}} ->
 	  UserList = make_userlist(Default, List),
@@ -155,11 +159,11 @@ process_blocklist_block(LUser, LServer, JIDs) ->
 	  {result, [], UserList};
       _Err ->
 	    ?ERROR_MSG("Error processing ~p: ~p", [{LUser, LServer, JIDs}, _Err]),
-	    {error, ?ERR_INTERNAL_SERVER_ERROR}
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)}
     end.
 
-process_blocklist_block(LUser, LServer, Filter,
-			mnesia) ->
+process_blocklist_block_db(LUser, LServer, Filter,
+			   mnesia) ->
     F = fun () ->
 		case mnesia:wread({privacy, {LUser, LServer}}) of
 		  [] ->
@@ -185,8 +189,8 @@ process_blocklist_block(LUser, LServer, Filter,
 		{ok, NewDefault, NewList}
 	end,
     mnesia:transaction(F);
-process_blocklist_block(LUser, LServer, Filter,
-			riak) ->
+process_blocklist_block_db(LUser, LServer, Filter,
+			   riak) ->
     {atomic,
      begin
          case ejabberd_riak:get(privacy, mod_privacy:privacy_schema(),
@@ -218,7 +222,7 @@ process_blocklist_block(LUser, LServer, Filter,
                  Err
          end
      end};
-process_blocklist_block(LUser, LServer, Filter, odbc) ->
+process_blocklist_block_db(LUser, LServer, Filter, odbc) ->
     F = fun () ->
 		Default = case
 			    mod_privacy:sql_get_default_privacy_list_t(LUser)
@@ -246,7 +250,7 @@ process_blocklist_block(LUser, LServer, Filter, odbc) ->
 	end,
     ejabberd_odbc:sql_transaction(LServer, F).
 
-process_blocklist_unblock_all(LUser, LServer) ->
+process_blocklist_unblock_all(LUser, LServer, Lang) ->
     Filter = fun (List) ->
 		     lists:filter(fun (#listitem{action = A}) -> A =/= deny
 				  end,
@@ -263,10 +267,10 @@ process_blocklist_unblock_all(LUser, LServer) ->
 	  {result, [], UserList};
       _Err ->
 	    ?ERROR_MSG("Error processing ~p: ~p", [{LUser, LServer}, _Err]),
-	    {error, ?ERR_INTERNAL_SERVER_ERROR}
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)}
     end.
 
-process_blocklist_unblock(LUser, LServer, JIDs) ->
+process_blocklist_unblock(LUser, LServer, JIDs, Lang) ->
     Filter = fun (List) ->
 		     lists:filter(fun (#listitem{action = deny, type = jid,
 						 value = JID}) ->
@@ -287,7 +291,7 @@ process_blocklist_unblock(LUser, LServer, JIDs) ->
 	  {result, [], UserList};
       _Err ->
 	    ?ERROR_MSG("Error processing ~p: ~p", [{LUser, LServer, JIDs}, _Err]),
-	    {error, ?ERR_INTERNAL_SERVER_ERROR}
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)}
     end.
 
 unblock_by_filter(LUser, LServer, Filter, mnesia) ->
@@ -375,11 +379,12 @@ broadcast_blocklist_event(LUser, LServer, Event) ->
     ejabberd_sm:route(JID, JID,
                       {broadcast, {blocking, Event}}).
 
-process_blocklist_get(LUser, LServer) ->
-    case process_blocklist_get(LUser, LServer,
-			       gen_mod:db_type(LServer, mod_privacy))
+process_blocklist_get(LUser, LServer, Lang) ->
+    case process_blocklist_get_db(LUser, LServer,
+				  gen_mod:db_type(LServer, mod_privacy))
 	of
-      error -> {error, ?ERR_INTERNAL_SERVER_ERROR};
+      error ->
+	  {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)};
       List ->
 	  JIDs = list_to_blocklist_jids(List, []),
 	  Items = lists:map(fun (JID) ->
@@ -397,7 +402,7 @@ process_blocklist_get(LUser, LServer) ->
 		   children = Items}]}
     end.
 
-process_blocklist_get(LUser, LServer, mnesia) ->
+process_blocklist_get_db(LUser, LServer, mnesia) ->
     case catch mnesia:dirty_read(privacy, {LUser, LServer})
 	of
       {'EXIT', _Reason} -> error;
@@ -408,7 +413,7 @@ process_blocklist_get(LUser, LServer, mnesia) ->
 	    _ -> []
 	  end
     end;
-process_blocklist_get(LUser, LServer, riak) ->
+process_blocklist_get_db(LUser, LServer, riak) ->
     case ejabberd_riak:get(privacy, mod_privacy:privacy_schema(),
 			   {LUser, LServer}) of
         {ok, #privacy{default = Default, lists = Lists}} ->
@@ -421,7 +426,7 @@ process_blocklist_get(LUser, LServer, riak) ->
         {error, _} ->
             error
     end;
-process_blocklist_get(LUser, LServer, odbc) ->
+process_blocklist_get_db(LUser, LServer, odbc) ->
     case catch
 	   mod_privacy:sql_get_default_privacy_list(LUser, LServer)
 	of
diff --git a/src/mod_carboncopy.erl b/src/mod_carboncopy.erl
index 81cf78a9..1e0499ee 100644
--- a/src/mod_carboncopy.erl
+++ b/src/mod_carboncopy.erl
@@ -102,7 +102,9 @@ iq_handler2(From, To, IQ) ->
 iq_handler1(From, To, IQ) ->
 	iq_handler(From, To, IQ, ?NS_CARBONS_1).
 
-iq_handler(From, _To,  #iq{type=set, sub_el = #xmlel{name = Operation, children = []}} = IQ, CC)->
+iq_handler(From, _To,
+	   #iq{type=set, lang = Lang,
+	       sub_el = #xmlel{name = Operation} = SubEl} = IQ, CC)->
     ?DEBUG("carbons IQ received: ~p", [IQ]),
     {U, S, R} = jid:tolower(From),
     Result = case Operation of
@@ -118,12 +120,14 @@ iq_handler(From, _To,  #iq{type=set, sub_el = #xmlel{name = Operation, children
 	    ?DEBUG("carbons IQ result: ok", []),
             IQ#iq{type=result, sub_el=[]};
 	{error,_Error} ->
-	    ?WARNING_MSG("Error enabling / disabling carbons: ~p", [Result]),
-            IQ#iq{type=error,sub_el = [?ERR_BAD_REQUEST]}
+	    ?ERROR_MSG("Error enabling / disabling carbons: ~p", [Result]),
+	    Txt = <<"Database failure">>,
+            IQ#iq{type=error,sub_el = [SubEl, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt)]}
     end;
 
-iq_handler(_From, _To, IQ, _CC)->
-    IQ#iq{type=error, sub_el = [?ERR_NOT_ALLOWED]}.
+iq_handler(_From, _To, #iq{lang = Lang, sub_el = SubEl} = IQ, _CC)->
+    Txt = <<"Value 'get' of 'type' attribute is not allowed">>,
+    IQ#iq{type=error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]}.
 
 user_send_packet(Packet, _C2SState, From, To) ->
     check_and_forward(From, To, Packet, sent).
diff --git a/src/mod_configure.erl b/src/mod_configure.erl
index 5e011704..a836c33b 100644
--- a/src/mod_configure.erl
+++ b/src/mod_configure.erl
@@ -198,81 +198,81 @@ get_local_identity(Acc, _From, _To, Node, Lang) ->
 
 %%%-----------------------------------------------------------------------
 
--define(INFO_RESULT(Allow, Feats),
+-define(INFO_RESULT(Allow, Feats, Lang),
 	case Allow of
-	  deny -> {error, ?ERR_FORBIDDEN};
+	  deny -> {error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
 	  allow -> {result, Feats}
 	end).
 
 get_sm_features(Acc, From,
-		#jid{lserver = LServer} = _To, Node, _Lang) ->
+		#jid{lserver = LServer} = _To, Node, Lang) ->
     case gen_mod:is_loaded(LServer, mod_adhoc) of
       false -> Acc;
       _ ->
 	  Allow = acl:match_rule(LServer, configure, From),
 	  case Node of
-	    <<"config">> -> ?INFO_RESULT(Allow, [?NS_COMMANDS]);
+	    <<"config">> -> ?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    _ -> Acc
 	  end
     end.
 
 get_local_features(Acc, From,
-		   #jid{lserver = LServer} = _To, Node, _Lang) ->
+		   #jid{lserver = LServer} = _To, Node, Lang) ->
     case gen_mod:is_loaded(LServer, mod_adhoc) of
       false -> Acc;
       _ ->
 	  LNode = tokenize(Node),
 	  Allow = acl:match_rule(LServer, configure, From),
 	  case LNode of
-	    [<<"config">>] -> ?INFO_RESULT(Allow, []);
-	    [<<"user">>] -> ?INFO_RESULT(Allow, []);
-	    [<<"online users">>] -> ?INFO_RESULT(Allow, []);
-	    [<<"all users">>] -> ?INFO_RESULT(Allow, []);
+	    [<<"config">>] -> ?INFO_RESULT(Allow, [], Lang);
+	    [<<"user">>] -> ?INFO_RESULT(Allow, [], Lang);
+	    [<<"online users">>] -> ?INFO_RESULT(Allow, [], Lang);
+	    [<<"all users">>] -> ?INFO_RESULT(Allow, [], Lang);
 	    [<<"all users">>, <<$@, _/binary>>] ->
-		?INFO_RESULT(Allow, []);
-	    [<<"outgoing s2s">> | _] -> ?INFO_RESULT(Allow, []);
-	    [<<"running nodes">>] -> ?INFO_RESULT(Allow, []);
-	    [<<"stopped nodes">>] -> ?INFO_RESULT(Allow, []);
+		?INFO_RESULT(Allow, [], Lang);
+	    [<<"outgoing s2s">> | _] -> ?INFO_RESULT(Allow, [], Lang);
+	    [<<"running nodes">>] -> ?INFO_RESULT(Allow, [], Lang);
+	    [<<"stopped nodes">>] -> ?INFO_RESULT(Allow, [], Lang);
 	    [<<"running nodes">>, _ENode] ->
-		?INFO_RESULT(Allow, [?NS_STATS]);
+		?INFO_RESULT(Allow, [?NS_STATS], Lang);
 	    [<<"running nodes">>, _ENode, <<"DB">>] ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    [<<"running nodes">>, _ENode, <<"modules">>] ->
-		?INFO_RESULT(Allow, []);
+		?INFO_RESULT(Allow, [], Lang);
 	    [<<"running nodes">>, _ENode, <<"modules">>, _] ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    [<<"running nodes">>, _ENode, <<"backup">>] ->
-		?INFO_RESULT(Allow, []);
+		?INFO_RESULT(Allow, [], Lang);
 	    [<<"running nodes">>, _ENode, <<"backup">>, _] ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    [<<"running nodes">>, _ENode, <<"import">>] ->
-		?INFO_RESULT(Allow, []);
+		?INFO_RESULT(Allow, [], Lang);
 	    [<<"running nodes">>, _ENode, <<"import">>, _] ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    [<<"running nodes">>, _ENode, <<"restart">>] ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    [<<"running nodes">>, _ENode, <<"shutdown">>] ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    [<<"config">>, _] ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"add-user">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"delete-user">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"end-user-session">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"get-user-password">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"change-user-password">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"get-user-lastlogin">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"user-stats">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"get-registered-users-num">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    ?NS_ADMINL(<<"get-online-users-num">>) ->
-		?INFO_RESULT(Allow, [?NS_COMMANDS]);
+		?INFO_RESULT(Allow, [?NS_COMMANDS], Lang);
 	    _ -> Acc
 	  end
     end.
@@ -318,7 +318,8 @@ get_sm_items(Acc, From,
 		{result,
 		 Items ++ Nodes ++ get_user_resources(User, Server)};
 	    {allow, <<"config">>} -> {result, []};
-	    {_, <<"config">>} -> {error, ?ERR_FORBIDDEN};
+	    {_, <<"config">>} ->
+		  {error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
 	    _ -> Acc
 	  end
     end.
@@ -448,63 +449,64 @@ get_local_items(Acc, From, #jid{lserver = LServer} = To,
       _ ->
 	  LNode = tokenize(Node),
 	  Allow = acl:match_rule(LServer, configure, From),
+	  Err = ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>),
 	  case LNode of
 	    [<<"config">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"user">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"online users">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"all users">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"all users">>, <<$@, _/binary>>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"outgoing s2s">> | _] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"stopped nodes">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"DB">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"modules">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"modules">>, _] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"backup">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"backup">>, _] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"import">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"import">>, _] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"restart">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"running nodes">>, _ENode, <<"shutdown">>] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    [<<"config">>, _] ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"add-user">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"delete-user">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"end-user-session">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"get-user-password">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"change-user-password">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"get-user-lastlogin">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"user-stats">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"get-registered-users-num">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    ?NS_ADMINL(<<"get-online-users-num">>) ->
-		?ITEMS_RESULT(Allow, LNode, {error, ?ERR_FORBIDDEN});
+		?ITEMS_RESULT(Allow, LNode, {error, Err});
 	    _ -> Acc
 	  end
     end.
@@ -562,33 +564,29 @@ get_local_items({_, Host}, [<<"all users">>], _Server,
 get_local_items({_, Host},
 		[<<"all users">>, <<$@, Diap/binary>>], _Server,
 		_Lang) ->
-    case catch ejabberd_auth:get_vh_registered_users(Host)
-	of
-      {'EXIT', _Reason} -> ?ERR_INTERNAL_SERVER_ERROR;
-      Users ->
-	  SUsers = lists:sort([{S, U} || {U, S} <- Users]),
-	  case catch begin
-		       [S1, S2] = ejabberd_regexp:split(Diap, <<"-">>),
-		       N1 = jlib:binary_to_integer(S1),
-		       N2 = jlib:binary_to_integer(S2),
-		       Sub = lists:sublist(SUsers, N1, N2 - N1 + 1),
-		       lists:map(fun ({S, U}) ->
-					 #xmlel{name = <<"item">>,
-						attrs =
-						    [{<<"jid">>,
-						      <<U/binary, "@",
-							S/binary>>},
-						     {<<"name">>,
-						      <<U/binary, "@",
-							S/binary>>}],
-						children = []}
-				 end,
-				 Sub)
-		     end
-	      of
-	    {'EXIT', _Reason} -> ?ERR_NOT_ACCEPTABLE;
-	    Res -> {result, Res}
-	  end
+    Users = ejabberd_auth:get_vh_registered_users(Host),
+    SUsers = lists:sort([{S, U} || {U, S} <- Users]),
+    case catch begin
+		   [S1, S2] = ejabberd_regexp:split(Diap, <<"-">>),
+		   N1 = jlib:binary_to_integer(S1),
+		   N2 = jlib:binary_to_integer(S2),
+		   Sub = lists:sublist(SUsers, N1, N2 - N1 + 1),
+		   lists:map(fun ({S, U}) ->
+				     #xmlel{name = <<"item">>,
+					    attrs =
+						[{<<"jid">>,
+						  <<U/binary, "@",
+						    S/binary>>},
+						 {<<"name">>,
+						  <<U/binary, "@",
+						    S/binary>>}],
+					    children = []}
+			     end,
+			     Sub)
+	       end
+    of
+	{'EXIT', _Reason} -> ?ERR_NOT_ACCEPTABLE;
+	Res -> {result, Res}
     end;
 get_local_items({_, Host}, [<<"outgoing s2s">>],
 		_Server, Lang) ->
@@ -826,33 +824,33 @@ get_stopped_nodes(_Lang) ->
 %%-------------------------------------------------------------------------
 
 -define(COMMANDS_RESULT(LServerOrGlobal, From, To,
-			Request),
+			Request, Lang),
 	case acl:match_rule(LServerOrGlobal, configure, From) of
-	  deny -> {error, ?ERR_FORBIDDEN};
+	  deny -> {error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
 	  allow -> adhoc_local_commands(From, To, Request)
 	end).
 
 adhoc_local_commands(Acc, From,
 		     #jid{lserver = LServer} = To,
-		     #adhoc_request{node = Node} = Request) ->
+		     #adhoc_request{node = Node, lang = Lang} = Request) ->
     LNode = tokenize(Node),
     case LNode of
       [<<"running nodes">>, _ENode, <<"DB">>] ->
-	  ?COMMANDS_RESULT(global, From, To, Request);
+	  ?COMMANDS_RESULT(global, From, To, Request, Lang);
       [<<"running nodes">>, _ENode, <<"modules">>, _] ->
-	  ?COMMANDS_RESULT(LServer, From, To, Request);
+	  ?COMMANDS_RESULT(LServer, From, To, Request, Lang);
       [<<"running nodes">>, _ENode, <<"backup">>, _] ->
-	  ?COMMANDS_RESULT(global, From, To, Request);
+	  ?COMMANDS_RESULT(global, From, To, Request, Lang);
       [<<"running nodes">>, _ENode, <<"import">>, _] ->
-	  ?COMMANDS_RESULT(global, From, To, Request);
+	  ?COMMANDS_RESULT(global, From, To, Request, Lang);
       [<<"running nodes">>, _ENode, <<"restart">>] ->
-	  ?COMMANDS_RESULT(global, From, To, Request);
+	  ?COMMANDS_RESULT(global, From, To, Request, Lang);
       [<<"running nodes">>, _ENode, <<"shutdown">>] ->
-	  ?COMMANDS_RESULT(global, From, To, Request);
+	  ?COMMANDS_RESULT(global, From, To, Request, Lang);
       [<<"config">>, _] ->
-	  ?COMMANDS_RESULT(LServer, From, To, Request);
+	  ?COMMANDS_RESULT(LServer, From, To, Request, Lang);
       ?NS_ADMINL(_) ->
-	  ?COMMANDS_RESULT(LServer, From, To, Request);
+	  ?COMMANDS_RESULT(LServer, From, To, Request, Lang);
       _ -> Acc
     end.
 
@@ -882,7 +880,8 @@ adhoc_local_commands(From,
 	   end;
        XData /= false, ActionIsExecute ->
 	   case jlib:parse_xdata_submit(XData) of
-	     invalid -> {error, ?ERR_BAD_REQUEST};
+	     invalid ->
+		 {error, ?ERRT_BAD_REQUEST(Lang, <<"Incorrect data form">>)};
 	     Fields ->
 		 case catch set_form(From, LServer, LNode, Lang, Fields)
 		     of
@@ -898,7 +897,8 @@ adhoc_local_commands(From,
 		   {error, Error} -> {error, Error}
 		 end
 	   end;
-       true -> {error, ?ERR_BAD_REQUEST}
+       true ->
+	  {error, ?ERRT_BAD_REQUEST(Lang, <<"Incorrect action or data form">>)}
     end.
 
 -define(TVFIELD(Type, Var, Val),
@@ -980,10 +980,14 @@ adhoc_local_commands(From,
 get_form(_Host, [<<"running nodes">>, ENode, <<"DB">>],
 	 Lang) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  case ejabberd_cluster:call(Node, mnesia, system_info, [tables]) of
-	    {badrpc, _Reason} ->
+	    {badrpc, Reason} ->
+		?ERROR_MSG("RPC call mnesia:system_info(tables) on node "
+			   "~s failed: ~p", [Node, Reason]),
 		{error, ?ERR_INTERNAL_SERVER_ERROR};
 	    Tables ->
 		STables = lists:sort(Tables),
@@ -1023,10 +1027,14 @@ get_form(Host,
 	 [<<"running nodes">>, ENode, <<"modules">>, <<"stop">>],
 	 Lang) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  case ejabberd_cluster:call(Node, gen_mod, loaded_modules, [Host]) of
-	    {badrpc, _Reason} ->
+	    {badrpc, Reason} ->
+		?ERROR_MSG("RPC call gen_mod:loaded_modules(~s) on node "
+			   "~s failed: ~p", [Host, Node, Reason]),
 		{error, ?ERR_INTERNAL_SERVER_ERROR};
 	    Modules ->
 		SModules = lists:sort(Modules),
@@ -1562,9 +1570,11 @@ get_form(_Host, _, _Lang) ->
     {error, ?ERR_SERVICE_UNAVAILABLE}.
 
 set_form(_From, _Host,
-	 [<<"running nodes">>, ENode, <<"DB">>], _Lang, XData) ->
+	 [<<"running nodes">>, ENode, <<"DB">>], Lang, XData) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  lists:foreach(fun ({SVar, SVals}) ->
 				Table = jlib:binary_to_atom(SVar),
@@ -1596,9 +1606,11 @@ set_form(_From, _Host,
     end;
 set_form(_From, Host,
 	 [<<"running nodes">>, ENode, <<"modules">>, <<"stop">>],
-	 _Lang, XData) ->
+	 Lang, XData) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  lists:foreach(fun ({Var, Vals}) ->
 				case Vals of
@@ -1615,12 +1627,16 @@ set_form(_From, Host,
 set_form(_From, Host,
 	 [<<"running nodes">>, ENode, <<"modules">>,
 	  <<"start">>],
-	 _Lang, XData) ->
+	 Lang, XData) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  case lists:keysearch(<<"modules">>, 1, XData) of
-	    false -> {error, ?ERR_BAD_REQUEST};
+	    false ->
+		Txt = <<"No 'modules' found in data form">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 	    {value, {_, Strings}} ->
 		String = lists:foldl(fun (S, Res) ->
 					     <<Res/binary, S/binary, "\n">>
@@ -1637,98 +1653,143 @@ set_form(_From, Host,
 					  end,
 					  Modules),
 			    {result, []};
-			_ -> {error, ?ERR_BAD_REQUEST}
+			_ -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Parse failed">>)}
 		      end;
-		  _ -> {error, ?ERR_BAD_REQUEST}
+		  _ -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Scan failed">>)}
 		end
 	  end
     end;
 set_form(_From, _Host,
 	 [<<"running nodes">>, ENode, <<"backup">>,
 	  <<"backup">>],
-	 _Lang, XData) ->
+	 Lang, XData) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  case lists:keysearch(<<"path">>, 1, XData) of
-	    false -> {error, ?ERR_BAD_REQUEST};
+	    false ->
+		Txt = <<"No 'path' found in data form">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 	    {value, {_, [String]}} ->
 		case ejabberd_cluster:call(Node, mnesia, backup, [String]) of
-		  {badrpc, _Reason} ->
+		  {badrpc, Reason} ->
+		      ?ERROR_MSG("RPC call mnesia:backup(~s) to node ~s "
+				 "failed: ~p", [String, Node, Reason]),
+		      {error, ?ERR_INTERNAL_SERVER_ERROR};
+		  {error, Reason} ->
+		      ?ERROR_MSG("RPC call mnesia:backup(~s) to node ~s "
+				 "failed: ~p", [String, Node, Reason]),
 		      {error, ?ERR_INTERNAL_SERVER_ERROR};
-		  {error, _Reason} -> {error, ?ERR_INTERNAL_SERVER_ERROR};
 		  _ -> {result, []}
 		end;
-	    _ -> {error, ?ERR_BAD_REQUEST}
+	    _ ->
+		Txt = <<"Incorrect value of 'path' in data form">>,
+	        {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end
     end;
 set_form(_From, _Host,
 	 [<<"running nodes">>, ENode, <<"backup">>,
 	  <<"restore">>],
-	 _Lang, XData) ->
+	 Lang, XData) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  case lists:keysearch(<<"path">>, 1, XData) of
-	    false -> {error, ?ERR_BAD_REQUEST};
+	    false ->
+		Txt = <<"No 'path' found in data form">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 	    {value, {_, [String]}} ->
 		case ejabberd_cluster:call(Node, ejabberd_admin, restore, [String])
 		    of
-		  {badrpc, _Reason} ->
+		  {badrpc, Reason} ->
+		      ?ERROR_MSG("RPC call ejabberd_admin:restore(~s) to node "
+				 "~s failed: ~p", [String, Node, Reason]),
+		      {error, ?ERR_INTERNAL_SERVER_ERROR};
+		  {error, Reason} ->
+		      ?ERROR_MSG("RPC call ejabberd_admin:restore(~s) to node "
+				 "~s failed: ~p", [String, Node, Reason]),
 		      {error, ?ERR_INTERNAL_SERVER_ERROR};
-		  {error, _Reason} -> {error, ?ERR_INTERNAL_SERVER_ERROR};
 		  _ -> {result, []}
 		end;
-	    _ -> {error, ?ERR_BAD_REQUEST}
+	    _ ->
+		Txt = <<"Incorrect value of 'path' in data form">>,
+	        {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end
     end;
 set_form(_From, _Host,
 	 [<<"running nodes">>, ENode, <<"backup">>,
 	  <<"textfile">>],
-	 _Lang, XData) ->
+	 Lang, XData) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  case lists:keysearch(<<"path">>, 1, XData) of
-	    false -> {error, ?ERR_BAD_REQUEST};
+	    false ->
+		Txt = <<"No 'path' found in data form">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 	    {value, {_, [String]}} ->
 		case ejabberd_cluster:call(Node, ejabberd_admin, dump_to_textfile,
 			      [String])
 		    of
-		  {badrpc, _Reason} ->
+		  {badrpc, Reason} ->
+		      ?ERROR_MSG("RPC call ejabberd_admin:dump_to_textfile(~s) "
+				 "to node ~s failed: ~p", [String, Node, Reason]),
+		      {error, ?ERR_INTERNAL_SERVER_ERROR};
+		  {error, Reason} ->
+		      ?ERROR_MSG("RPC call ejabberd_admin:dump_to_textfile(~s) "
+				 "to node ~s failed: ~p", [String, Node, Reason]),
 		      {error, ?ERR_INTERNAL_SERVER_ERROR};
-		  {error, _Reason} -> {error, ?ERR_INTERNAL_SERVER_ERROR};
 		  _ -> {result, []}
 		end;
-	    _ -> {error, ?ERR_BAD_REQUEST}
+	    _ ->
+		Txt = <<"Incorrect value of 'path' in data form">>,
+	        {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end
     end;
 set_form(_From, _Host,
 	 [<<"running nodes">>, ENode, <<"import">>, <<"file">>],
-	 _Lang, XData) ->
+	 Lang, XData) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  case lists:keysearch(<<"path">>, 1, XData) of
-	    false -> {error, ?ERR_BAD_REQUEST};
+	    false ->
+		Txt = <<"No 'path' found in data form">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 	    {value, {_, [String]}} ->
 		ejabberd_cluster:call(Node, jd2ejd, import_file, [String]),
 		{result, []};
-	    _ -> {error, ?ERR_BAD_REQUEST}
+	    _ ->
+		Txt = <<"Incorrect value of 'path' in data form">>,
+	        {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end
     end;
 set_form(_From, _Host,
 	 [<<"running nodes">>, ENode, <<"import">>, <<"dir">>],
-	 _Lang, XData) ->
+	 Lang, XData) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	  Txt = <<"No running node found">>,
+	  {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  case lists:keysearch(<<"path">>, 1, XData) of
-	    false -> {error, ?ERR_BAD_REQUEST};
+	    false ->
+		Txt = <<"No 'path' found in data form">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 	    {value, {_, [String]}} ->
 		ejabberd_cluster:call(Node, jd2ejd, import_dir, [String]),
 		{result, []};
-	    _ -> {error, ?ERR_BAD_REQUEST}
+	    _ ->
+		Txt = <<"Incorrect value of 'path' in data form">>,
+	        {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end
     end;
 set_form(From, Host,
@@ -1739,7 +1800,7 @@ set_form(From, Host,
 	 [<<"running nodes">>, ENode, <<"shutdown">>], _Lang,
 	 XData) ->
     stop_node(From, Host, ENode, stop, XData);
-set_form(_From, Host, [<<"config">>, <<"acls">>], _Lang,
+set_form(_From, Host, [<<"config">>, <<"acls">>], Lang,
 	 XData) ->
     case lists:keysearch(<<"acls">>, 1, XData) of
       {value, {_, Strings}} ->
@@ -1753,14 +1814,16 @@ set_form(_From, Host, [<<"config">>, <<"acls">>], _Lang,
 		  {ok, ACLs} ->
 		      acl:add_list(Host, ACLs, true),
                       {result, []};
-		  _ -> {error, ?ERR_BAD_REQUEST}
+		  _ -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Parse failed">>)}
 		end;
-	    _ -> {error, ?ERR_BAD_REQUEST}
+	    _ -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Scan failed">>)}
 	  end;
-      _ -> {error, ?ERR_BAD_REQUEST}
+      _ ->
+	  Txt = <<"No 'acls' found in data form">>,
+	  {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
     end;
 set_form(_From, Host, [<<"config">>, <<"access">>],
-	 _Lang, XData) ->
+	 Lang, XData) ->
     SetAccess = fun (Rs) ->
 			mnesia:transaction(fun () ->
 						   Os = mnesia:select(local_config,
@@ -1803,11 +1866,13 @@ set_form(_From, Host, [<<"config">>, <<"access">>],
 			{atomic, _} -> {result, []};
 			_ -> {error, ?ERR_BAD_REQUEST}
 		      end;
-		  _ -> {error, ?ERR_BAD_REQUEST}
+		  _ -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Parse failed">>)}
 		end;
-	    _ -> {error, ?ERR_BAD_REQUEST}
+	    _ -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Scan failed">>)}
 	  end;
-      _ -> {error, ?ERR_BAD_REQUEST}
+      _ ->
+	  Txt = <<"No 'access' found in data form">>,
+	  {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
     end;
 set_form(From, Host, ?NS_ADMINL(<<"add-user">>), _Lang,
 	 XData) ->
@@ -2052,7 +2117,7 @@ adhoc_sm_commands(_Acc, From,
 				 action = Action, xdata = XData} =
 		      Request) ->
     case acl:match_rule(LServer, configure, From) of
-      deny -> {error, ?ERR_FORBIDDEN};
+      deny -> {error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
       allow ->
 	  ActionIsExecute = lists:member(Action,
 					 [<<"">>, <<"execute">>,
@@ -2071,11 +2136,15 @@ adhoc_sm_commands(_Acc, From,
 		 end;
 	     XData /= false, ActionIsExecute ->
 		 case jlib:parse_xdata_submit(XData) of
-		   invalid -> {error, ?ERR_BAD_REQUEST};
+		   invalid ->
+		       Txt = <<"Incorrect data form">>,
+		       {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 		   Fields ->
 		       set_sm_form(User, Server, <<"config">>, Request, Fields)
 		 end;
-	     true -> {error, ?ERR_BAD_REQUEST}
+	     true ->
+		Txt = <<"Incorrect action or data form">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end
     end;
 adhoc_sm_commands(Acc, _From, _To, _Request) -> Acc.
@@ -2135,12 +2204,16 @@ set_sm_form(User, Server, <<"config">>,
 	    {value, {_, [Password]}} ->
 		ejabberd_auth:set_password(User, Server, Password),
 		adhoc:produce_response(Response);
-	    _ -> {error, ?ERR_NOT_ACCEPTABLE}
+	    _ ->
+		Txt = <<"No 'password' found in data form">>,
+		{error, ?ERRT_NOT_ACCEPTABLE(Lang, Txt)}
 	  end;
       {value, {_, [<<"remove">>]}} ->
 	  catch ejabberd_auth:remove_user(User, Server),
 	  adhoc:produce_response(Response);
-      _ -> {error, ?ERR_NOT_ACCEPTABLE}
+      _ ->
+	  Txt = <<"Incorrect value of 'action' in data form">>,
+	  {error, ?ERRT_NOT_ACCEPTABLE(Lang, Txt)}
     end;
 set_sm_form(_User, _Server, _Node, _Request, _Fields) ->
     {error, ?ERR_SERVICE_UNAVAILABLE}.
diff --git a/src/mod_configure2.erl b/src/mod_configure2.erl
index 0acd4a78..a8287b4d 100644
--- a/src/mod_configure2.erl
+++ b/src/mod_configure2.erl
@@ -56,15 +56,17 @@ stop(Host) ->
 				     ?NS_ECONFIGURE).
 
 process_local_iq(From, To,
-		 #iq{type = Type, lang = _Lang, sub_el = SubEl} = IQ) ->
+		 #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case acl:match_rule(To#jid.lserver, configure, From) of
       deny ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Denied by ACL">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       allow ->
 	  case Type of
 	    set ->
+		Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_FEATURE_NOT_IMPLEMENTED]};
+		      sub_el = [SubEl, ?ERRT_FEATURE_NOT_IMPLEMENTED(Lang, Txt)]};
 	    %%case fxml:get_tag_attr_s("type", SubEl) of
 	    %%    "cancel" ->
 	    %%        IQ#iq{type = result,
@@ -98,7 +100,7 @@ process_local_iq(From, To,
 	    %%		   sub_el = [SubEl, ?ERR_NOT_ALLOWED]}
 	    %%end;
 	    get ->
-		case process_get(SubEl) of
+		case process_get(SubEl, Lang) of
 		  {result, Res} -> IQ#iq{type = result, sub_el = [Res]};
 		  {error, Error} ->
 		      IQ#iq{type = error, sub_el = [SubEl, Error]}
@@ -106,7 +108,7 @@ process_local_iq(From, To,
 	  end
     end.
 
-process_get(#xmlel{name = <<"info">>}) ->
+process_get(#xmlel{name = <<"info">>}, _Lang) ->
     S2SConns = ejabberd_s2s:dirty_get_connections(),
     TConns = lists:usort([element(2, C) || C <- S2SConns]),
     Attrs = [{<<"registered-users">>,
@@ -130,7 +132,7 @@ process_get(#xmlel{name = <<"info">>}) ->
 	    attrs = [{<<"xmlns">>, ?NS_ECONFIGURE} | Attrs],
 	    children = []}};
 process_get(#xmlel{name = <<"welcome-message">>,
-		   attrs = Attrs}) ->
+		   attrs = Attrs}, _Lang) ->
     {Subj, Body} = ejabberd_config:get_option(
                      welcome_message,
                      fun({Subj, Body}) ->
@@ -146,7 +148,7 @@ process_get(#xmlel{name = <<"welcome-message">>,
 		 #xmlel{name = <<"body">>, attrs = [],
 			children = [{xmlcdata, Body}]}]}};
 process_get(#xmlel{name = <<"registration-watchers">>,
-		   attrs = Attrs}) ->
+		   attrs = Attrs}, _Lang) ->
     SubEls = ejabberd_config:get_option(
                registration_watchers,
                fun(JIDs) when is_list(JIDs) ->
@@ -160,14 +162,14 @@ process_get(#xmlel{name = <<"registration-watchers">>,
     {result,
      #xmlel{name = <<"registration_watchers">>,
 	    attrs = Attrs, children = SubEls}};
-process_get(#xmlel{name = <<"acls">>, attrs = Attrs}) ->
+process_get(#xmlel{name = <<"acls">>, attrs = Attrs}, _Lang) ->
     Str = iolist_to_binary(io_lib:format("~p.",
 					 [ets:tab2list(acl)])),
     {result,
      #xmlel{name = <<"acls">>, attrs = Attrs,
 	    children = [{xmlcdata, Str}]}};
 process_get(#xmlel{name = <<"access">>,
-		   attrs = Attrs}) ->
+		   attrs = Attrs}, _Lang) ->
     Str = iolist_to_binary(io_lib:format("~p.",
 					 [ets:select(local_config,
 						     [{{local_config, {access, '$1'},
@@ -178,13 +180,14 @@ process_get(#xmlel{name = <<"access">>,
     {result,
      #xmlel{name = <<"access">>, attrs = Attrs,
 	    children = [{xmlcdata, Str}]}};
-process_get(#xmlel{name = <<"last">>, attrs = Attrs}) ->
+process_get(#xmlel{name = <<"last">>, attrs = Attrs}, Lang) ->
     case catch mnesia:dirty_select(last_activity,
 				   [{{last_activity, '_', '$1', '_'}, [],
 				     ['$1']}])
 	of
       {'EXIT', _Reason} ->
-	  {error, ?ERR_INTERNAL_SERVER_ERROR};
+	  Txt = <<"Database failure">>,
+	  {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt)};
       Vals ->
 	  TimeStamp = p1_time_compat:system_time(seconds),
 	  Str = list_to_binary(
@@ -196,7 +199,7 @@ process_get(#xmlel{name = <<"last">>, attrs = Attrs}) ->
     end;
 %%process_get({xmlelement, Name, Attrs, SubEls}) ->
 %%    {result, };
-process_get(_) -> {error, ?ERR_BAD_REQUEST}.
+process_get(_, _) -> {error, ?ERR_BAD_REQUEST}.
 
 mod_opt_type(iqdisc) -> fun gen_iq_handler:check_type/1;
 mod_opt_type(_) -> [iqdisc].
diff --git a/src/mod_disco.erl b/src/mod_disco.erl
index 734e90d3..0d5abcb4 100644
--- a/src/mod_disco.erl
+++ b/src/mod_disco.erl
@@ -150,7 +150,8 @@ process_local_iq_items(From, To,
 		       #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  Node = fxml:get_tag_attr_s(<<"node">>, SubEl),
 	  Host = To#jid.lserver,
@@ -177,7 +178,8 @@ process_local_iq_info(From, To,
 		      #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  Host = To#jid.lserver,
 	  Node = fxml:get_tag_attr_s(<<"node">>, SubEl),
@@ -229,10 +231,12 @@ get_local_features(Acc, _From, To, <<>>, _Lang) ->
      ets:select(disco_features,
 		[{{{'_', Host}}, [], ['$_']}])
        ++ Feats};
-get_local_features(Acc, _From, _To, _Node, _Lang) ->
+get_local_features(Acc, _From, _To, _Node, Lang) ->
     case Acc of
       {result, _Features} -> Acc;
-      empty -> {error, ?ERR_ITEM_NOT_FOUND}
+      empty ->
+	    Txt = <<"No features available">>,
+	    {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)}
     end.
 
 features_to_xml(FeatureList) ->
@@ -271,8 +275,8 @@ get_local_services(Acc, _From, To, <<>>, _Lang) ->
 get_local_services({result, _} = Acc, _From, _To, _Node,
 		   _Lang) ->
     Acc;
-get_local_services(empty, _From, _To, _Node, _Lang) ->
-    {error, ?ERR_ITEM_NOT_FOUND}.
+get_local_services(empty, _From, _To, _Node, Lang) ->
+    {error, ?ERRT_ITEM_NOT_FOUND(Lang, <<"No services available">>)}.
 
 get_vh_services(Host) ->
     Hosts = lists:sort(fun (H1, H2) ->
@@ -300,7 +304,8 @@ process_sm_iq_items(From, To,
 		    #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  case is_presence_subscribed(From, To) of
 	    true ->
@@ -325,8 +330,9 @@ process_sm_iq_items(From, To,
 		      IQ#iq{type = error, sub_el = [SubEl, Error]}
 		end;
 	    false ->
+		Txt = <<"Not subscribed">>,
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_SERVICE_UNAVAILABLE]}
+		      sub_el = [SubEl, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)]}
 	  end
     end.
 
@@ -347,12 +353,14 @@ get_sm_items(Acc, From,
 get_sm_items({result, _} = Acc, _From, _To, _Node,
 	     _Lang) ->
     Acc;
-get_sm_items(empty, From, To, _Node, _Lang) ->
+get_sm_items(empty, From, To, _Node, Lang) ->
     #jid{luser = LFrom, lserver = LSFrom} = From,
     #jid{luser = LTo, lserver = LSTo} = To,
     case {LFrom, LSFrom} of
       {LTo, LSTo} -> {error, ?ERR_ITEM_NOT_FOUND};
-      _ -> {error, ?ERR_NOT_ALLOWED}
+      _ ->
+	    Txt = <<"Query to another users is forbidden">>,
+	    {error, ?ERRT_NOT_ALLOWED(Lang, Txt)}
     end.
 
 is_presence_subscribed(#jid{luser = User, lserver = Server},
@@ -373,7 +381,8 @@ process_sm_iq_info(From, To,
 		   #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  case is_presence_subscribed(From, To) of
 	    true ->
@@ -405,8 +414,9 @@ process_sm_iq_info(From, To,
 		      IQ#iq{type = error, sub_el = [SubEl, Error]}
 		end;
 	    false ->
+		Txt = <<"Not subscribed">>,
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_SERVICE_UNAVAILABLE]}
+		      sub_el = [SubEl, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)]}
 	  end
     end.
 
@@ -423,12 +433,14 @@ get_sm_identity(Acc, _From,
 	_ -> []
       end.
 
-get_sm_features(empty, From, To, _Node, _Lang) ->
+get_sm_features(empty, From, To, _Node, Lang) ->
     #jid{luser = LFrom, lserver = LSFrom} = From,
     #jid{luser = LTo, lserver = LSTo} = To,
     case {LFrom, LSFrom} of
       {LTo, LSTo} -> {error, ?ERR_ITEM_NOT_FOUND};
-      _ -> {error, ?ERR_NOT_ALLOWED}
+      _ ->
+	    Txt = <<"Query to another users is forbidden">>,
+	    {error, ?ERRT_NOT_ALLOWED(Lang, Txt)}
     end;
 get_sm_features(Acc, _From, _To, _Node, _Lang) -> Acc.
 
diff --git a/src/mod_echo.erl b/src/mod_echo.erl
index 7184ee4e..7d9f81f8 100644
--- a/src/mod_echo.erl
+++ b/src/mod_echo.erl
@@ -118,7 +118,10 @@ handle_cast(_Msg, State) -> {noreply, State}.
 handle_info({route, From, To, Packet}, State) ->
     Packet2 = case From#jid.user of
 		<<"">> ->
-		    jlib:make_error_reply(Packet, ?ERR_BAD_REQUEST);
+		    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
+		    Txt = <<"User part of JID in 'from' is empty">>,
+		    jlib:make_error_reply(
+		      Packet, ?ERRT_BAD_REQUEST(Lang, Txt));
 		_ -> Packet
 	      end,
     do_client_version(disabled, To, From),
diff --git a/src/mod_http_upload.erl b/src/mod_http_upload.erl
index 6c029c43..214badca 100644
--- a/src/mod_http_upload.erl
+++ b/src/mod_http_upload.erl
@@ -569,7 +569,8 @@ process_iq(From,
 	deny ->
 	    ?DEBUG("Denying HTTP upload slot request from ~s",
 		   [jid:to_string(From)]),
-	    IQ#iq{type = error, sub_el = [SubEl, ?ERR_FORBIDDEN]}
+	    Txt = <<"Denied by ACL">>,
+	    IQ#iq{type = error, sub_el = [SubEl, ?ERRT_FORBIDDEN(Lang, Txt)]}
     end;
 process_iq(_From, #iq{sub_el = SubEl} = IQ, _State) ->
     IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
@@ -601,7 +602,8 @@ parse_request(#xmlel{name = <<"request">>, attrs = Attrs} = Request, Lang) ->
 		    {error, ?ERRT_BAD_REQUEST(Lang, Text)}
 	    end;
 	_ ->
-	    {error, ?ERR_BAD_REQUEST}
+	    Text = <<"No or invalid XML namespace">>,
+	    {error, ?ERRT_BAD_REQUEST(Lang, Text)}
     end;
 parse_request(_El, _Lang) -> {error, ?ERR_BAD_REQUEST}.
 
@@ -639,7 +641,7 @@ create_slot(#state{service_url = undefined,
     end;
 create_slot(#state{service_url = ServiceURL},
 	    #jid{luser = U, lserver = S} = JID, File, Size, ContentType,
-	    _Lang) ->
+	    Lang) ->
     Options = [{body_format, binary}, {full_result, false}],
     HttpOptions = [{timeout, ?SERVICE_REQUEST_TIMEOUT}],
     SizeStr = jlib:integer_to_binary(Size),
@@ -659,7 +661,8 @@ create_slot(#state{service_url = ServiceURL},
 		Lines ->
 		    ?ERROR_MSG("Can't parse data received for ~s from <~s>: ~p",
 			       [jid:to_string(JID), ServiceURL, Lines]),
-		    {error, ?ERR_SERVICE_UNAVAILABLE}
+		    Txt = <<"Failed to parse HTTP response">>,
+		    {error, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)}
 	    end;
 	{ok, {402, _Body}} ->
 	    ?INFO_MSG("Got status code 402 for ~s from <~s>",
diff --git a/src/mod_irc.erl b/src/mod_irc.erl
index d5cd0135..f6e452d8 100644
--- a/src/mod_irc.erl
+++ b/src/mod_irc.erl
@@ -304,8 +304,9 @@ do_route1(Host, ServerHost, From, To, Packet) ->
 									Lang)}]},
 			    Res = jlib:iq_to_xml(ResIQ);
 			_ ->
-			    Res = jlib:make_error_reply(Packet,
-							?ERR_ITEM_NOT_FOUND)
+			    Txt = <<"Node not found">>,
+			    Res = jlib:make_error_reply(
+				    Packet, ?ERRT_ITEM_NOT_FOUND(Lang, Txt))
 		      end,
 		      ejabberd_router:route(To, From, Res);
 		  #iq{xmlns = ?NS_REGISTER} = IQ ->
@@ -319,7 +320,7 @@ do_route1(Host, ServerHost, From, To, Packet) ->
 					      attrs = [{<<"xmlns">>, XMLNS}],
 					      children = iq_get_vcard(Lang)}]},
 		      ejabberd_router:route(To, From, jlib:iq_to_xml(Res));
-		  #iq{type = set, xmlns = ?NS_COMMANDS, lang = _Lang,
+		  #iq{type = set, xmlns = ?NS_COMMANDS, lang = Lang,
 		      sub_el = SubEl} =
 		      IQ ->
 		      Request = adhoc:parse_request(IQ),
@@ -348,8 +349,9 @@ do_route1(Host, ServerHost, From, To, Packet) ->
 			       true -> ok
 			    end;
 			_ ->
-			    Err = jlib:make_error_reply(Packet,
-							?ERR_ITEM_NOT_FOUND),
+			    Txt = <<"Node not found">>,
+			    Err = jlib:make_error_reply(
+				    Packet, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)),
 			    ejabberd_router:route(To, From, Err)
 		      end;
 		  #iq{} = _IQ ->
@@ -407,12 +409,14 @@ do_route1(Host, ServerHost, From, To, Packet) ->
 		      ok
 		end;
 	    _ ->
+		Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
 		case str:tokens(ChanServ, <<"!">>) of
 		  [<<_, _/binary>> = Nick, <<_, _/binary>> = Server] ->
 		      case ets:lookup(irc_connection, {From, Server, Host}) of
 			[] ->
-			    Err = jlib:make_error_reply(Packet,
-							?ERR_SERVICE_UNAVAILABLE),
+			    Txt = <<"IRC connection not found">>,
+			    Err = jlib:make_error_reply(
+				    Packet, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)),
 			    ejabberd_router:route(To, From, Err);
 			[R] ->
 			    Pid = R#irc_connection.pid,
@@ -421,7 +425,9 @@ do_route1(Host, ServerHost, From, To, Packet) ->
 			    ok
 		      end;
 		  _ ->
-		      Err = jlib:make_error_reply(Packet, ?ERR_BAD_REQUEST),
+		      Txt = <<"Failed to parse chanserv">>,
+		      Err = jlib:make_error_reply(
+			      Packet, ?ERRT_BAD_REQUEST(Lang, Txt)),
 		      ejabberd_router:route(To, From, Err)
 		end
 	  end
@@ -532,8 +538,9 @@ process_irc_register(ServerHost, Host, From, _To,
 	  XDataEl = find_xdata_el(SubEl),
 	  case XDataEl of
 	    false ->
+		Txt1 = <<"No data form found">>,
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_NOT_ACCEPTABLE]};
+		      sub_el = [SubEl, ?ERRT_NOT_ACCEPTABLE(Lang, Txt1)]};
 	    #xmlel{attrs = Attrs} ->
 		case fxml:get_attr_s(<<"type">>, Attrs) of
 		  <<"cancel">> ->
@@ -546,8 +553,9 @@ process_irc_register(ServerHost, Host, From, _To,
 		      XData = jlib:parse_xdata_submit(XDataEl),
 		      case XData of
 			invalid ->
+			    Txt2 = <<"Incorrect data form">>,
 			    IQ#iq{type = error,
-				  sub_el = [SubEl, ?ERR_BAD_REQUEST]};
+				  sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt2)]};
 			_ ->
 			    Node = str:tokens(fxml:get_tag_attr_s(<<"node">>,
 								 SubEl),
@@ -567,7 +575,9 @@ process_irc_register(ServerHost, Host, From, _To,
 			    end
 		      end;
 		  _ ->
-		      IQ#iq{type = error, sub_el = [SubEl, ?ERR_BAD_REQUEST]}
+		      Txt3 = <<"Incorrect value of 'type' attribute">>,
+		      IQ#iq{type = error,
+			    sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt3)]}
 		end
 	  end;
       get ->
@@ -629,7 +639,9 @@ get_form(ServerHost, Host, From, [], Lang) ->
     #jid{user = User, server = Server} = From,
     DefaultEncoding = get_default_encoding(Host),
     Customs = case get_data(ServerHost, Host, From) of
-		error -> {error, ?ERR_INTERNAL_SERVER_ERROR};
+		error ->
+		      Txt1 = <<"Database failure">>,
+		      {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt1)};
 		empty -> {User, []};
 		Data -> get_username_and_connection_params(Data)
 	      end,
@@ -763,7 +775,7 @@ set_data(LServer, Host, From, Data, odbc) ->
 	end,
     ejabberd_odbc:sql_transaction(LServer, F).
 
-set_form(ServerHost, Host, From, [], _Lang, XData) ->
+set_form(ServerHost, Host, From, [], Lang, XData) ->
     case {lists:keysearch(<<"username">>, 1, XData),
 	  lists:keysearch(<<"connections_params">>, 1, XData)}
 	of
@@ -781,11 +793,11 @@ set_form(ServerHost, Host, From, [], _Lang, XData) ->
 				     {connections_params, ConnectionsParams}])
 			  of
 			{atomic, _} -> {result, []};
-			_ -> {error, ?ERR_NOT_ACCEPTABLE}
+			_ -> {error, ?ERRT_NOT_ACCEPTABLE(Lang, <<"Database failure">>)}
 		      end;
-		  _ -> {error, ?ERR_NOT_ACCEPTABLE}
+		  _ -> {error, ?ERRT_NOT_ACCEPTABLE(Lang, <<"Parse error">>)}
 		end;
-	    _ -> {error, ?ERR_NOT_ACCEPTABLE}
+	    _ -> {error, ?ERRT_NOT_ACCEPTABLE(Lang, <<"Scan error">>)}
 	  end;
       _ -> {error, ?ERR_NOT_ACCEPTABLE}
     end;
@@ -909,7 +921,9 @@ adhoc_join(From, To,
 						  elements = [Form]});
        true ->
 	   case jlib:parse_xdata_submit(XData) of
-	     invalid -> {error, ?ERR_BAD_REQUEST};
+	     invalid ->
+		 Txt1 = <<"Incorrect data form">>,
+		 {error, ?ERRT_BAD_REQUEST(Lang, Txt1)};
 	     Fields ->
 		 Channel = case lists:keysearch(<<"channel">>, 1, Fields)
 			       of
@@ -998,7 +1012,8 @@ adhoc_register(ServerHost, From, To,
        true ->
 	   case jlib:parse_xdata_submit(XData) of
 	     invalid ->
-		 Error = {error, ?ERR_BAD_REQUEST},
+		 Txt1 = <<"Incorrect data form">>,
+		 Error = {error, ?ERRT_BAD_REQUEST(Lang, Txt1)},
 		 Username = false,
 		 ConnectionsParams = false;
 	     Fields ->
@@ -1021,7 +1036,9 @@ adhoc_register(ServerHost, From, To,
 	     {atomic, _} ->
 		 adhoc:produce_response(Request,
 					#adhoc_response{status = completed});
-	     _ -> {error, ?ERR_INTERNAL_SERVER_ERROR}
+	     _ ->
+		 Txt2 = <<"Database failure">>,
+		 {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt2)}
 	   end;
        true ->
 	   Form = generate_adhoc_register_form(Lang, Username,
diff --git a/src/mod_last.erl b/src/mod_last.erl
index 33f88e02..009a1cb0 100644
--- a/src/mod_last.erl
+++ b/src/mod_last.erl
@@ -86,10 +86,11 @@ stop(Host) ->
 %%%
 
 process_local_iq(_From, _To,
-		 #iq{type = Type, sub_el = SubEl} = IQ) ->
+		 #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  Sec = get_node_uptime(),
 	  IQ#iq{type = result,
@@ -123,10 +124,11 @@ now_to_seconds({MegaSecs, Secs, _MicroSecs}) ->
 %%%
 
 process_sm_iq(From, To,
-	      #iq{type = Type, sub_el = SubEl} = IQ) ->
+	      #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  User = To#jid.luser,
 	  Server = To#jid.lserver,
@@ -153,7 +155,8 @@ process_sm_iq(From, To,
 		       IQ#iq{type = error, sub_el = [SubEl, ?ERR_FORBIDDEN]}
 		 end;
 	     true ->
-		 IQ#iq{type = error, sub_el = [SubEl, ?ERR_FORBIDDEN]}
+		 Txt = <<"Not subscribed">>,
+		 IQ#iq{type = error, sub_el = [SubEl, ?ERRT_FORBIDDEN(Lang, Txt)]}
 	  end
     end.
 
@@ -193,16 +196,18 @@ get_last(LUser, LServer, odbc) ->
         Reason -> {error, {invalid_result, Reason}}
     end.
 
-get_last_iq(IQ, SubEl, LUser, LServer) ->
+get_last_iq(#iq{lang = Lang} = IQ, SubEl, LUser, LServer) ->
     case ejabberd_sm:get_user_resources(LUser, LServer) of
       [] ->
 	  case get_last(LUser, LServer) of
 	    {error, _Reason} ->
+		Txt = <<"Database failure">>,
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_INTERNAL_SERVER_ERROR]};
+		      sub_el = [SubEl, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt)]};
 	    not_found ->
+		Txt = <<"No info about last activity found">>,
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_SERVICE_UNAVAILABLE]};
+		      sub_el = [SubEl, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)]};
 	    {ok, TimeStamp, Status} ->
 		TimeStamp2 = p1_time_compat:system_time(seconds),
 		Sec = TimeStamp2 - TimeStamp,
diff --git a/src/mod_mam.erl b/src/mod_mam.erl
index d212f63c..862adee9 100644
--- a/src/mod_mam.erl
+++ b/src/mod_mam.erl
@@ -447,7 +447,7 @@ process_iq(LServer, #iq{sub_el = #xmlel{attrs = Attrs}} = IQ) ->
 % Preference setting (both v0.2 & v0.3)
 process_iq(#jid{luser = LUser, lserver = LServer},
 	   #jid{lserver = LServer},
-	   #iq{type = set, sub_el = #xmlel{name = <<"prefs">>} = SubEl} = IQ) ->
+	   #iq{type = set, lang = Lang, sub_el = #xmlel{name = <<"prefs">>} = SubEl} = IQ) ->
     try {case fxml:get_tag_attr_s(<<"default">>, SubEl) of
 	    <<"always">> -> always;
 	    <<"never">> -> never;
@@ -469,8 +469,9 @@ process_iq(#jid{luser = LUser, lserver = LServer},
 		    NewPrefs = prefs_el(Default, Always, Never, IQ#iq.xmlns),
 		    IQ#iq{type = result, sub_el = [NewPrefs]};
 		_Err ->
+		    Txt = <<"Database failure">>,
 		    IQ#iq{type = error,
-			sub_el = [SubEl, ?ERR_INTERNAL_SERVER_ERROR]}
+			sub_el = [SubEl, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt)]}
 	    end
     catch _:_ ->
 	    IQ#iq{type = error, sub_el = [SubEl, ?ERR_BAD_REQUEST]}
diff --git a/src/mod_mix.erl b/src/mod_mix.erl
index d8cf94ac..c0835b74 100644
--- a/src/mod_mix.erl
+++ b/src/mod_mix.erl
@@ -132,8 +132,9 @@ process_iq(From, To,
 	{error, Err} ->
 	    IQ#iq{type = error, sub_el = [SubEl, Err]}
     end;
-process_iq(_From, _To, #iq{sub_el = SubEl} = IQ) ->
-    IQ#iq{type = error, sub_el = [SubEl, ?ERR_BAD_REQUEST]}.
+process_iq(_From, _To, #iq{sub_el = SubEl, lang = Lang} = IQ) ->
+    Txt = <<"Unsupported MIX query">>,
+    IQ#iq{type = error, sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt)]}.
 
 %%%===================================================================
 %%% gen_server callbacks
diff --git a/src/mod_muc.erl b/src/mod_muc.erl
index 0d37a236..9d4b4985 100644
--- a/src/mod_muc.erl
+++ b/src/mod_muc.erl
@@ -1056,7 +1056,9 @@ iq_set_register_info(ServerHost, Host, From, Nick,
 	  ErrText = <<"That nickname is registered by another "
 		      "person">>,
 	  {error, ?ERRT_CONFLICT(Lang, ErrText)};
-      _ -> {error, ?ERR_INTERNAL_SERVER_ERROR}
+      _ ->
+	  Txt = <<"Database failure">>,
+	  {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt)}
     end.
 
 process_iq_register_set(ServerHost, Host, From, SubEl,
@@ -1073,7 +1075,9 @@ process_iq_register_set(ServerHost, Host, From, SubEl,
 		  {?NS_XDATA, <<"submit">>} ->
 		      XData = jlib:parse_xdata_submit(XEl),
 		      case XData of
-			invalid -> {error, ?ERR_BAD_REQUEST};
+			invalid ->
+			      Txt = <<"Incorrect data form">>,
+			      {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 			_ ->
 			    case lists:keysearch(<<"nick">>, 1, XData) of
 			      {value, {_, [Nick]}} when Nick /= <<"">> ->
diff --git a/src/mod_muc_room.erl b/src/mod_muc_room.erl
index 06fdf325..c9c78575 100644
--- a/src/mod_muc_room.erl
+++ b/src/mod_muc_room.erl
@@ -252,7 +252,7 @@ normal_state({route, From, <<"">>,
 		IsVoiceApprovement = is_voice_approvement(Els) and
 				       not is_visitor(From, StateData),
 		if IsInvitation ->
-		       case catch check_invitation(From, Els, Lang, StateData)
+		       case catch check_invitation(From, Packet, Lang, StateData)
 			   of
 			 {error, Error} ->
 			     Err = jlib:make_error_reply(Packet, Error),
@@ -433,9 +433,11 @@ normal_state({route, From, <<"">>,
 				   process_iq_owner(From, Type, Lang, SubEl, StateData);
 			       ?NS_DISCO_INFO ->
 				   case fxml:get_attr(<<"node">>, Attrs) of
-					  false -> process_iq_disco_info(From, Type, Lang, StateData);
-					  {value, _} -> {error, ?ERR_SERVICE_UNAVAILABLE}
-					end;
+				       false -> process_iq_disco_info(From, Type, Lang, StateData);
+				       {value, _} ->
+					   Txt = <<"Disco info is not available for this node">>,
+					   {error, ?ERRT_SERVICE_UNAVAILABLE(Lang, Txt)}
+				   end;
 			       ?NS_DISCO_ITEMS ->
 				   process_iq_disco_items(From, Type, Lang, StateData);
 			       ?NS_VCARD ->
@@ -817,8 +819,9 @@ handle_info({captcha_failed, From}, normal_state,
 		   of
 		 {ok, {Nick, Packet}} ->
 		     Robots = (?DICT):erase(From, StateData#state.robots),
-		     Err = jlib:make_error_reply(Packet,
-						 ?ERR_NOT_AUTHORIZED),
+		     Txt = <<"The CAPTCHA verification has failed">>,
+		     Err = jlib:make_error_reply(
+			     Packet, ?ERRT_NOT_AUTHORIZED(?MYLANG, Txt)),
 		     ejabberd_router:route % TODO: s/Nick/""/
 				 (jid:replace_resource(StateData#state.jid,
 							    Nick),
@@ -1807,6 +1810,22 @@ add_new_user(From, Nick,
 			       StateData#state.host, From, Nick),
 	  get_default_role(Affiliation, StateData)}
 	of
+      {false, _, _, _} when NUsers >= MaxUsers orelse NUsers >= MaxAdminUsers ->
+	  Txt = <<"Too many users in this conference">>,
+	  Err = jlib:make_error_reply(Packet,
+				      ?ERRT_RESOURCE_CONSTRAINT(Lang, Txt)),
+	  ejabberd_router:route % TODO: s/Nick/""/
+		      (jid:replace_resource(StateData#state.jid, Nick),
+		       From, Err),
+	  StateData;
+      {false, _, _, _} when NConferences >= MaxConferences ->
+	  Txt = <<"You have joined too many conferences">>,
+	  Err = jlib:make_error_reply(Packet,
+				      ?ERRT_RESOURCE_CONSTRAINT(Lang, Txt)),
+	  ejabberd_router:route % TODO: s/Nick/""/
+		      (jid:replace_resource(StateData#state.jid, Nick),
+		       From, Err),
+	  StateData;
       {false, _, _, _} ->
 	  Err = jlib:make_error_reply(Packet,
 				      ?ERR_SERVICE_UNAVAILABLE),
@@ -2555,14 +2574,18 @@ process_iq_admin(From, set, Lang, SubEl, StateData) ->
     process_admin_items_set(From, Items, Lang, StateData);
 process_iq_admin(From, get, Lang, SubEl, StateData) ->
     case fxml:get_subtag(SubEl, <<"item">>) of
-      false -> {error, ?ERR_BAD_REQUEST};
+      false ->
+	  Txt = <<"No 'item' element found">>,
+	  {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
       Item ->
 	  FAffiliation = get_affiliation(From, StateData),
 	  FRole = get_role(From, StateData),
 	  case fxml:get_tag_attr(<<"role">>, Item) of
 	    false ->
 		case fxml:get_tag_attr(<<"affiliation">>, Item) of
-		  false -> {error, ?ERR_BAD_REQUEST};
+		  false ->
+		      Txt = <<"No 'affiliation' attribute found">>,
+		      {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 		  {value, StrAffiliation} ->
 		      case catch list_to_affiliation(StrAffiliation) of
 			{'EXIT', _} -> {error, ?ERR_BAD_REQUEST};
@@ -2583,7 +2606,9 @@ process_iq_admin(From, get, Lang, SubEl, StateData) ->
 		end;
 	    {value, StrRole} ->
 		case catch list_to_role(StrRole) of
-		  {'EXIT', _} -> {error, ?ERR_BAD_REQUEST};
+		  {'EXIT', _} ->
+		      Txt = <<"Incorrect value of 'role' attribute">>,
+		      {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 		  SRole ->
 		      if FRole == moderator ->
 			     Items = items_with_role(SRole, StateData),
@@ -2780,7 +2805,9 @@ find_changed_items(UJID, UAffiliation, URole,
 			     {error, ?ERRT_NOT_ACCEPTABLE(Lang, ErrText)};
 			 J -> {value, J}
 		       end;
-		   _ -> {error, ?ERR_BAD_REQUEST}
+		   _ ->
+		       Txt1 = <<"No 'nick' attribute found">>,
+		       {error, ?ERRT_BAD_REQUEST(Lang, Txt1)}
 		 end
 	   end,
     case TJID of
@@ -2790,7 +2817,9 @@ find_changed_items(UJID, UAffiliation, URole,
 	  case fxml:get_attr(<<"role">>, Attrs) of
 	    false ->
 		case fxml:get_attr(<<"affiliation">>, Attrs) of
-		  false -> {error, ?ERR_BAD_REQUEST};
+		  false ->
+		      Txt2 = <<"No 'affiliation' attribute found">>,
+		      {error, ?ERRT_BAD_REQUEST(Lang, Txt2)};
 		  {value, StrAffiliation} ->
 		      case catch list_to_affiliation(StrAffiliation) of
 			{'EXIT', _} ->
@@ -2839,7 +2868,9 @@ find_changed_items(UJID, UAffiliation, URole,
 				  find_changed_items(UJID, UAffiliation, URole,
 						     Items, Lang, StateData,
 						     [MoreRes | Res]);
-			      false -> {error, ?ERR_NOT_ALLOWED}
+			      false ->
+				 Txt3 = <<"Changing role/affiliation is not allowed">>,
+				 {error, ?ERRT_NOT_ALLOWED(Lang, Txt3)}
 			    end
 		      end
 		end;
@@ -2885,7 +2916,9 @@ find_changed_items(UJID, UAffiliation, URole,
 			    find_changed_items(UJID, UAffiliation, URole, Items,
 					       Lang, StateData,
 					       [MoreRes | Res]);
-			_ -> {error, ?ERR_NOT_ALLOWED}
+			_ ->
+			   Txt4 = <<"Changing role/affiliation is not allowed">>,
+			   {error, ?ERRT_NOT_ALLOWED(Lang, Txt4)}
 		      end
 		end
 	  end;
@@ -3143,10 +3176,12 @@ process_iq_owner(From, set, Lang, SubEl, StateData) ->
 				 andalso
 				 is_password_settings_correct(XEl, StateData)
 			  of
-			true -> set_config(XEl, StateData);
+			true -> set_config(XEl, StateData, Lang);
 			false -> {error, ?ERR_NOT_ACCEPTABLE}
 		      end;
-		  _ -> {error, ?ERR_BAD_REQUEST}
+		  _ ->
+		     Txt = <<"Incorrect data form">>,
+		     {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 		end;
 	    [#xmlel{name = <<"destroy">>} = SubEl1] ->
 		?INFO_MSG("Destroyed MUC room ~s by the owner ~s",
@@ -3170,7 +3205,9 @@ process_iq_owner(From, get, Lang, SubEl, StateData) ->
 	    [] -> get_config(Lang, StateData, From);
 	    [Item] ->
 		case fxml:get_tag_attr(<<"affiliation">>, Item) of
-		  false -> {error, ?ERR_BAD_REQUEST};
+		  false ->
+		      Txt = <<"No 'affiliation' attribute found">>,
+		      {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 		  {value, StrAffiliation} ->
 		      case catch list_to_affiliation(StrAffiliation) of
 			{'EXIT', _} ->
@@ -3642,10 +3679,10 @@ get_config(Lang, StateData, From) ->
 	     children = Res}],
      StateData}.
 
-set_config(XEl, StateData) ->
+set_config(XEl, StateData, Lang) ->
     XData = jlib:parse_xdata_submit(XEl),
     case XData of
-      invalid -> {error, ?ERR_BAD_REQUEST};
+      invalid -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Incorrect data form">>)};
       _ ->
 	  case set_xoption(XData, StateData#state.config) of
 	    #config{} = Config ->
@@ -3675,14 +3712,20 @@ set_config(XEl, StateData) ->
 	  <<"1">> -> set_xoption(Opts, Config#config{Opt = true});
 	  <<"true">> ->
 	      set_xoption(Opts, Config#config{Opt = true});
-	  _ -> {error, ?ERR_BAD_REQUEST}
+	  _ ->
+	      Txt = <<"Value of '~s' should be boolean">>,
+	      ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	      {error, ?ERRT_BAD_REQUEST(?MYLANG, ErrTxt)}
 	end).
 
 -define(SET_NAT_XOPT(Opt, Val),
 	case catch jlib:binary_to_integer(Val) of
 	  I when is_integer(I), I > 0 ->
 	      set_xoption(Opts, Config#config{Opt = I});
-	  _ -> {error, ?ERR_BAD_REQUEST}
+	  _ ->
+	      Txt = <<"Value of '~s' should be integer">>,
+	      ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	      {error, ?ERRT_BAD_REQUEST(?MYLANG, ErrTxt)}
 	end).
 
 -define(SET_STRING_XOPT(Opt, Val),
@@ -3735,7 +3778,10 @@ set_xoption([{<<"allow_private_messages_from_visitors">>,
       <<"nobody">> ->
 	  ?SET_STRING_XOPT(allow_private_messages_from_visitors,
 			   nobody);
-      _ -> {error, ?ERR_BAD_REQUEST}
+      _ ->
+	  Txt = <<"Value of 'allow_private_messages_from_visitors' "
+		  "should be anyone|moderators|nobody">>,
+	  {error, ?ERRT_BAD_REQUEST(?MYLANG, Txt)}
     end;
 set_xoption([{<<"muc#roomconfig_allowvisitorstatus">>,
 	      [Val]}
@@ -3803,7 +3849,10 @@ set_xoption([{<<"muc#roomconfig_presencebroadcast">>, Vals} | Opts],
                   end
           end, {false, false, false}, Vals),
     case Roles of
-        error -> {error, ?ERR_BAD_REQUEST};
+        error ->
+	    Txt = <<"Value of 'muc#roomconfig_presencebroadcast' should "
+		    "be moderator|participant|visitor">>,
+	    {error, ?ERRT_BAD_REQUEST(?MYLANG, Txt)};
         {M, P, V} ->
             Res =
                 if M -> [moderator]; true -> [] end ++
@@ -3831,7 +3880,10 @@ set_xoption([{<<"muc#roomconfig_whois">>, [Val]}
       <<"anyone">> ->
 	  ?SET_BOOL_XOPT(anonymous,
 			 (iolist_to_binary(integer_to_list(0))));
-      _ -> {error, ?ERR_BAD_REQUEST}
+      _ ->
+	  Txt = <<"Value of 'muc#roomconfig_whois' should be "
+		  "moderators|anyone">>,
+	  {error, ?ERRT_BAD_REQUEST(?MYLANG, Txt)}
     end;
 set_xoption([{<<"muc#roomconfig_maxusers">>, [Val]}
 	     | Opts],
@@ -3854,8 +3906,10 @@ set_xoption([{<<"muc#roomconfig_captcha_whitelist">>,
     ?SET_JIDMULTI_XOPT(captcha_whitelist, JIDs);
 set_xoption([{<<"FORM_TYPE">>, _} | Opts], Config) ->
     set_xoption(Opts, Config);
-set_xoption([_ | _Opts], _Config) ->
-    {error, ?ERR_BAD_REQUEST}.
+set_xoption([{Opt, _Vals} | _Opts], _Config) ->
+    Txt = <<"Unknown option '~s'">>,
+    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+    {error, ?ERRT_BAD_REQUEST(?MYLANG, ErrTxt)}.
 
 change_config(Config, StateData) ->
     send_config_change_info(Config, StateData),
@@ -4128,8 +4182,9 @@ destroy_room(DEl, StateData) ->
 	  false -> ?FEATURE(Fiffalse)
 	end).
 
-process_iq_disco_info(_From, set, _Lang, _StateData) ->
-    {error, ?ERR_NOT_ALLOWED};
+process_iq_disco_info(_From, set, Lang, _StateData) ->
+    Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+    {error, ?ERRT_NOT_ALLOWED(Lang, Txt)};
 process_iq_disco_info(_From, get, Lang, StateData) ->
     Config = StateData#state.config,
     {result,
@@ -4199,9 +4254,10 @@ iq_disco_info_extras(Lang, StateData) ->
 			 <<"muc#roominfo_occupants">>,
 			 (iolist_to_binary(integer_to_list(Len))))]}].
 
-process_iq_disco_items(_From, set, _Lang, _StateData) ->
-    {error, ?ERR_NOT_ALLOWED};
-process_iq_disco_items(From, get, _Lang, StateData) ->
+process_iq_disco_items(_From, set, Lang, _StateData) ->
+    Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+    {error, ?ERRT_NOT_ALLOWED(Lang, Txt)};
+process_iq_disco_items(From, get, Lang, StateData) ->
     case (StateData#state.config)#config.public_list of
       true ->
 	  {result, get_mucroom_disco_items(StateData), StateData};
@@ -4209,18 +4265,26 @@ process_iq_disco_items(From, get, _Lang, StateData) ->
 	  case is_occupant_or_admin(From, StateData) of
 	    true ->
 		{result, get_mucroom_disco_items(StateData), StateData};
-	    _ -> {error, ?ERR_FORBIDDEN}
+	    _ ->
+	        Txt = <<"Only occupants or administrators can perform this query">>,
+		{error, ?ERRT_FORBIDDEN(Lang, Txt)}
 	  end
     end.
 
-process_iq_captcha(_From, get, _Lang, _SubEl,
+process_iq_captcha(_From, get, Lang, _SubEl,
 		   _StateData) ->
-    {error, ?ERR_NOT_ALLOWED};
-process_iq_captcha(_From, set, _Lang, SubEl,
+    Txt = <<"Value 'get' of 'type' attribute is not allowed">>,
+    {error, ?ERRT_NOT_ALLOWED(Lang, Txt)};
+process_iq_captcha(_From, set, Lang, SubEl,
 		   StateData) ->
     case ejabberd_captcha:process_reply(SubEl) of
       ok -> {result, [], StateData};
-      _ -> {error, ?ERR_NOT_ACCEPTABLE}
+      {error, malformed} ->
+	    Txt = <<"Incorrect CAPTCHA submit">>,
+	    {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
+      _ ->
+	    Txt = <<"The CAPTCHA verification has failed">>,
+	    {error, ?ERRT_NOT_ALLOWED(Lang, Txt)}
     end.
 
 process_iq_vcard(_From, get, _Lang, _SubEl, StateData) ->
@@ -4442,33 +4506,38 @@ is_invitation(Els) ->
 		end,
 		false, Els).
 
-check_invitation(From, Els, Lang, StateData) ->
+check_invitation(From, Packet, Lang, StateData) ->
     FAffiliation = get_affiliation(From, StateData),
     CanInvite =
 	(StateData#state.config)#config.allow_user_invites
 	  orelse
 	  FAffiliation == admin orelse FAffiliation == owner,
-    InviteEl = case fxml:remove_cdata(Els) of
-		 [#xmlel{name = <<"x">>, children = Els1} = XEl] ->
-		     case fxml:get_tag_attr_s(<<"xmlns">>, XEl) of
-		       ?NS_MUC_USER -> ok;
-		       _ -> throw({error, ?ERR_BAD_REQUEST})
-		     end,
-		     case fxml:remove_cdata(Els1) of
-		       [#xmlel{name = <<"invite">>} = InviteEl1] -> InviteEl1;
-		       _ -> throw({error, ?ERR_BAD_REQUEST})
-		     end;
-		 _ -> throw({error, ?ERR_BAD_REQUEST})
+    InviteEl = case fxml:get_subtag_with_xmlns(Packet, <<"x">>, ?NS_MUC_USER) of
+		   false ->
+		       Txt1 = <<"No 'x' element found">>,
+		       throw({error, ?ERRT_BAD_REQUEST(Lang, Txt1)});
+		   XEl ->
+		       case fxml:get_subtag(XEl, <<"invite">>) of
+			   false ->
+			       Txt2 = <<"No 'invite' element found">>,
+			       throw({error, ?ERRT_BAD_REQUEST(Lang, Txt2)});
+			   InviteEl1 ->
+			       InviteEl1
+		       end
 	       end,
     JID = case
 	    jid:from_string(fxml:get_tag_attr_s(<<"to">>,
 						  InviteEl))
 	      of
-	    error -> throw({error, ?ERR_JID_MALFORMED});
+	    error ->
+		  Txt = <<"Incorrect value of 'to' attribute">>,
+		  throw({error, ?ERRT_JID_MALFORMED(Lang, Txt)});
 	    JID1 -> JID1
 	  end,
     case CanInvite of
-      false -> throw({error, ?ERR_NOT_ALLOWED});
+      false ->
+	  Txt3 = <<"Invitations are not allowed in this conference">>,
+	  throw({error, ?ERRT_NOT_ALLOWED(Lang, Txt3)});
       true ->
 	  Reason = fxml:get_path_s(InviteEl,
 				  [{elem, <<"reason">>}, cdata]),
diff --git a/src/mod_offline.erl b/src/mod_offline.erl
index fa6a961f..54eda165 100644
--- a/src/mod_offline.erl
+++ b/src/mod_offline.erl
@@ -387,8 +387,9 @@ handle_offline_query(#jid{luser = U, lserver = S} = From,
 	    end
     end,
     IQ#iq{type = result, sub_el = []};
-handle_offline_query(_From, _To, #iq{sub_el = SubEl} = IQ) ->
-    IQ#iq{type = error, sub_el = [SubEl, ?ERR_FORBIDDEN]}.
+handle_offline_query(_From, _To, #iq{sub_el = SubEl, lang = Lang} = IQ) ->
+    Txt = <<"Query to another users is forbidden">>,
+    IQ#iq{type = error, sub_el = [SubEl, ?ERRT_FORBIDDEN(Lang, Txt)]}.
 
 handle_offline_items_view(JID, #xmlel{children = Items}) ->
     {U, S, R} = jid:tolower(JID),
diff --git a/src/mod_ping.erl b/src/mod_ping.erl
index e8a977de..305c6a69 100644
--- a/src/mod_ping.erl
+++ b/src/mod_ping.erl
@@ -204,13 +204,14 @@ code_change(_OldVsn, State, _Extra) -> {ok, State}.
 %% Hook callbacks
 %%====================================================================
 iq_ping(_From, _To,
-	#iq{type = Type, sub_el = SubEl} = IQ) ->
+	#iq{type = Type, sub_el = SubEl, lang = Lang} = IQ) ->
     case {Type, SubEl} of
       {get, #xmlel{name = <<"ping">>}} ->
 	  IQ#iq{type = result, sub_el = []};
       _ ->
+	  Txt = <<"Ping query is incorrect">>,
 	  IQ#iq{type = error,
-		sub_el = [SubEl, ?ERR_FEATURE_NOT_IMPLEMENTED]}
+		sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt)]}
     end.
 
 user_online(_SID, JID, _Info) ->
diff --git a/src/mod_privacy.erl b/src/mod_privacy.erl
index 193befe8..ea36fed2 100644
--- a/src/mod_privacy.erl
+++ b/src/mod_privacy.erl
@@ -105,27 +105,29 @@ process_iq(_From, _To, IQ) ->
     SubEl = IQ#iq.sub_el,
     IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]}.
 
-process_iq_get(_, From, _To, #iq{sub_el = SubEl},
+process_iq_get(_, From, _To, #iq{lang = Lang, sub_el = SubEl},
 	       #userlist{name = Active}) ->
     #jid{luser = LUser, lserver = LServer} = From,
     #xmlel{children = Els} = SubEl,
     case fxml:remove_cdata(Els) of
-      [] -> process_lists_get(LUser, LServer, Active);
+      [] -> process_lists_get(LUser, LServer, Active, Lang);
       [#xmlel{name = Name, attrs = Attrs}] ->
 	  case Name of
 	    <<"list">> ->
 		ListName = fxml:get_attr(<<"name">>, Attrs),
-		process_list_get(LUser, LServer, ListName);
-	    _ -> {error, ?ERR_BAD_REQUEST}
+		process_list_get(LUser, LServer, ListName, Lang);
+	    _ ->
+		  Txt = <<"Unsupported tag name">>,
+		  {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end;
-      _ -> {error, ?ERR_BAD_REQUEST}
+      _ -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Too many elements">>)}
     end.
 
-process_lists_get(LUser, LServer, Active) ->
-    case process_lists_get(LUser, LServer, Active,
+process_lists_get(LUser, LServer, Active, Lang) ->
+    case process_lists_get_db(LUser, LServer, Active,
 			   gen_mod:db_type(LServer, ?MODULE))
 	of
-      error -> {error, ?ERR_INTERNAL_SERVER_ERROR};
+      error -> {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)};
       {_Default, []} ->
 	  {result,
 	   [#xmlel{name = <<"query">>,
@@ -151,7 +153,7 @@ process_lists_get(LUser, LServer, Active) ->
 		   children = ADItems}]}
     end.
 
-process_lists_get(LUser, LServer, _Active, mnesia) ->
+process_lists_get_db(LUser, LServer, _Active, mnesia) ->
     case catch mnesia:dirty_read(privacy, {LUser, LServer})
 	of
       {'EXIT', _Reason} -> error;
@@ -165,7 +167,7 @@ process_lists_get(LUser, LServer, _Active, mnesia) ->
 			     Lists),
 	  {Default, LItems}
     end;
-process_lists_get(LUser, LServer, _Active, riak) ->
+process_lists_get_db(LUser, LServer, _Active, riak) ->
     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
         {ok, #privacy{default = Default, lists = Lists}} ->
             LItems = lists:map(fun ({N, _}) ->
@@ -180,7 +182,7 @@ process_lists_get(LUser, LServer, _Active, riak) ->
         {error, _} ->
             error
     end;
-process_lists_get(LUser, LServer, _Active, odbc) ->
+process_lists_get_db(LUser, LServer, _Active, odbc) ->
     Default = case catch sql_get_default_privacy_list(LUser, LServer) of
 		{selected, []} -> none;
 		{selected, [{DefName}]} -> DefName;
@@ -198,11 +200,11 @@ process_lists_get(LUser, LServer, _Active, odbc) ->
       _ -> error
     end.
 
-process_list_get(LUser, LServer, {value, Name}) ->
-    case process_list_get(LUser, LServer, Name,
+process_list_get(LUser, LServer, {value, Name}, Lang) ->
+    case process_list_get_db(LUser, LServer, Name,
 			  gen_mod:db_type(LServer, ?MODULE))
 	of
-      error -> {error, ?ERR_INTERNAL_SERVER_ERROR};
+      error -> {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)};
       not_found -> {error, ?ERR_ITEM_NOT_FOUND};
       Items ->
 	  LItems = lists:map(fun item_to_xml/1, Items),
@@ -213,10 +215,10 @@ process_list_get(LUser, LServer, {value, Name}) ->
 		       [#xmlel{name = <<"list">>, attrs = [{<<"name">>, Name}],
 			       children = LItems}]}]}
     end;
-process_list_get(_LUser, _LServer, false) ->
+process_list_get(_LUser, _LServer, false, _Lang) ->
     {error, ?ERR_BAD_REQUEST}.
 
-process_list_get(LUser, LServer, Name, mnesia) ->
+process_list_get_db(LUser, LServer, Name, mnesia) ->
     case catch mnesia:dirty_read(privacy, {LUser, LServer})
 	of
       {'EXIT', _Reason} -> error;
@@ -227,7 +229,7 @@ process_list_get(LUser, LServer, Name, mnesia) ->
 	    _ -> not_found
 	  end
     end;
-process_list_get(LUser, LServer, Name, riak) ->
+process_list_get_db(LUser, LServer, Name, riak) ->
     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
         {ok, #privacy{lists = Lists}} ->
             case lists:keysearch(Name, 1, Lists) of
@@ -239,7 +241,7 @@ process_list_get(LUser, LServer, Name, riak) ->
         {error, _} ->
             error
     end;
-process_list_get(LUser, LServer, Name, odbc) ->
+process_list_get_db(LUser, LServer, Name, odbc) ->
     case catch sql_get_privacy_list_id(LUser, LServer, Name) of
       {selected, []} -> not_found;
       {selected, [{ID}]} ->
@@ -332,7 +334,7 @@ list_to_action(S) ->
       <<"deny">> -> deny
     end.
 
-process_iq_set(_, From, _To, #iq{sub_el = SubEl}) ->
+process_iq_set(_, From, _To, #iq{lang = Lang, sub_el = SubEl}) ->
     #jid{luser = LUser, lserver = LServer} = From,
     #xmlel{children = Els} = SubEl,
     case fxml:remove_cdata(Els) of
@@ -342,27 +344,30 @@ process_iq_set(_, From, _To, #iq{sub_el = SubEl}) ->
 	  case Name of
 	    <<"list">> ->
 		process_list_set(LUser, LServer, ListName,
-				 fxml:remove_cdata(SubEls));
+				 fxml:remove_cdata(SubEls), Lang);
 	    <<"active">> ->
 		process_active_set(LUser, LServer, ListName);
 	    <<"default">> ->
-		process_default_set(LUser, LServer, ListName);
-	    _ -> {error, ?ERR_BAD_REQUEST}
+		process_default_set(LUser, LServer, ListName, Lang);
+	    _ ->
+		Txt = <<"Unsupported tag name">>,
+		{error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	  end;
       _ -> {error, ?ERR_BAD_REQUEST}
     end.
 
-process_default_set(LUser, LServer, Value) ->
-    case process_default_set(LUser, LServer, Value,
+process_default_set(LUser, LServer, Value, Lang) ->
+    case process_default_set_db(LUser, LServer, Value,
 			     gen_mod:db_type(LServer, ?MODULE))
 	of
-      {atomic, error} -> {error, ?ERR_INTERNAL_SERVER_ERROR};
+      {atomic, error} ->
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)};
       {atomic, not_found} -> {error, ?ERR_ITEM_NOT_FOUND};
       {atomic, ok} -> {result, []};
       _ -> {error, ?ERR_INTERNAL_SERVER_ERROR}
     end.
 
-process_default_set(LUser, LServer, {value, Name},
+process_default_set_db(LUser, LServer, {value, Name},
 		    mnesia) ->
     F = fun () ->
 		case mnesia:read({privacy, {LUser, LServer}}) of
@@ -378,7 +383,7 @@ process_default_set(LUser, LServer, {value, Name},
 		end
 	end,
     mnesia:transaction(F);
-process_default_set(LUser, LServer, {value, Name}, riak) ->
+process_default_set_db(LUser, LServer, {value, Name}, riak) ->
     {atomic,
      case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
          {ok, #privacy{lists = Lists} = P} ->
@@ -393,7 +398,7 @@ process_default_set(LUser, LServer, {value, Name}, riak) ->
          {error, _} ->
              not_found
      end};
-process_default_set(LUser, LServer, {value, Name},
+process_default_set_db(LUser, LServer, {value, Name},
 		    odbc) ->
     F = fun () ->
 		case sql_get_privacy_list_names_t(LUser) of
@@ -406,7 +411,7 @@ process_default_set(LUser, LServer, {value, Name},
 		end
 	end,
     odbc_queries:sql_transaction(LServer, F);
-process_default_set(LUser, LServer, false, mnesia) ->
+process_default_set_db(LUser, LServer, false, mnesia) ->
     F = fun () ->
 		case mnesia:read({privacy, {LUser, LServer}}) of
 		  [] -> ok;
@@ -414,7 +419,7 @@ process_default_set(LUser, LServer, false, mnesia) ->
 		end
 	end,
     mnesia:transaction(F);
-process_default_set(LUser, LServer, false, riak) ->
+process_default_set_db(LUser, LServer, false, riak) ->
     {atomic,
      case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
          {ok, R} ->
@@ -422,7 +427,7 @@ process_default_set(LUser, LServer, false, riak) ->
          {error, _} ->
              ok
      end};
-process_default_set(LUser, LServer, false, odbc) ->
+process_default_set_db(LUser, LServer, false, odbc) ->
     case catch sql_unset_default_privacy_list(LUser,
 					      LServer)
 	of
@@ -588,14 +593,16 @@ set_privacy_list(LUser, LServer, Name, List, odbc) ->
 	end,
     odbc_queries:sql_transaction(LServer, F).
 
-process_list_set(LUser, LServer, {value, Name}, Els) ->
+process_list_set(LUser, LServer, {value, Name}, Els, Lang) ->
     case parse_items(Els) of
       false -> {error, ?ERR_BAD_REQUEST};
       remove ->
 	  case remove_privacy_list(LUser, LServer, Name,
 				   gen_mod:db_type(LServer, ?MODULE))
 	      of
-	    {atomic, conflict} -> {error, ?ERR_CONFLICT};
+	    {atomic, conflict} ->
+		  Txt = <<"Cannot remove default list">>,
+		  {error, ?ERRT_CONFLICT(Lang, Txt)};
 	    {atomic, ok} ->
 		ejabberd_sm:route(jid:make(LUser, LServer,
                                                 <<"">>),
@@ -605,7 +612,7 @@ process_list_set(LUser, LServer, {value, Name}, Els) ->
                                                          list = []},
                                                Name}}),
 		{result, []};
-	    _ -> {error, ?ERR_INTERNAL_SERVER_ERROR}
+	    _ -> {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)}
 	  end;
       List ->
 	  case set_privacy_list(LUser, LServer, Name, List,
@@ -622,10 +629,10 @@ process_list_set(LUser, LServer, {value, Name}, Els) ->
                                                          needdb = NeedDb},
                                                Name}}),
 		{result, []};
-	    _ -> {error, ?ERR_INTERNAL_SERVER_ERROR}
+	    _ -> {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)}
 	  end
     end;
-process_list_set(_LUser, _LServer, false, _Els) ->
+process_list_set(_LUser, _LServer, false, _Els, _Lang) ->
     {error, ?ERR_BAD_REQUEST}.
 
 parse_items([]) -> remove;
diff --git a/src/mod_private.erl b/src/mod_private.erl
index f3dceeaa..b4b06450 100644
--- a/src/mod_private.erl
+++ b/src/mod_private.erl
@@ -73,52 +73,58 @@ stop(Host) ->
 				     ?NS_PRIVATE).
 
 process_sm_iq(#jid{luser = LUser, lserver = LServer},
-	      #jid{luser = LUser, lserver = LServer}, IQ)
+	      #jid{luser = LUser, lserver = LServer}, #iq{lang = Lang} = IQ)
     when IQ#iq.type == set ->
     case IQ#iq.sub_el of
       #xmlel{name = <<"query">>, children = Xmlels} ->
 	  case filter_xmlels(Xmlels) of
 	    [] ->
+		Txt = <<"No private data found in this query">>,
 		IQ#iq{type = error,
-		      sub_el = [IQ#iq.sub_el, ?ERR_NOT_ACCEPTABLE]};
+		      sub_el = [IQ#iq.sub_el, ?ERRT_NOT_ACCEPTABLE(Lang, Txt)]};
 	    Data ->
 		set_data(LUser, LServer, Data),
 		IQ#iq{type = result, sub_el = []}
 	  end;
       _ ->
+	  Txt = <<"No query found">>,
 	  IQ#iq{type = error,
-		sub_el = [IQ#iq.sub_el, ?ERR_NOT_ACCEPTABLE]}
+		sub_el = [IQ#iq.sub_el, ?ERRT_NOT_ACCEPTABLE(Lang, Txt)]}
     end;
 %%
 process_sm_iq(#jid{luser = LUser, lserver = LServer},
-	      #jid{luser = LUser, lserver = LServer}, IQ)
+	      #jid{luser = LUser, lserver = LServer}, #iq{lang = Lang} = IQ)
     when IQ#iq.type == get ->
     case IQ#iq.sub_el of
       #xmlel{name = <<"query">>, attrs = Attrs,
 	     children = Xmlels} ->
 	  case filter_xmlels(Xmlels) of
 	    [] ->
+		Txt = <<"No private data found in this query">>,
 		IQ#iq{type = error,
-		      sub_el = [IQ#iq.sub_el, ?ERR_BAD_FORMAT]};
+		      sub_el = [IQ#iq.sub_el, ?ERRT_BAD_FORMAT(Lang, Txt)]};
 	    Data ->
 		case catch get_data(LUser, LServer, Data) of
 		  {'EXIT', _Reason} ->
+		      Txt = <<"Database failure">>,
 		      IQ#iq{type = error,
 			    sub_el =
-				[IQ#iq.sub_el, ?ERR_INTERNAL_SERVER_ERROR]};
+				[IQ#iq.sub_el, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt)]};
 		  Storage_Xmlels ->
 		      IQ#iq{type = result,
 			    sub_el = [?Xmlel_Query(Attrs, Storage_Xmlels)]}
 		end
 	  end;
       _ ->
+	  Txt = <<"No query found">>,
 	  IQ#iq{type = error,
-		sub_el = [IQ#iq.sub_el, ?ERR_BAD_FORMAT]}
+		sub_el = [IQ#iq.sub_el, ?ERRT_BAD_FORMAT(Lang, Txt)]}
     end;
 %%
-process_sm_iq(_From, _To, IQ) ->
+process_sm_iq(_From, _To, #iq{lang = Lang} = IQ) ->
+    Txt = <<"Query to another users is forbidden">>,
     IQ#iq{type = error,
-	  sub_el = [IQ#iq.sub_el, ?ERR_FORBIDDEN]}.
+	  sub_el = [IQ#iq.sub_el, ?ERRT_FORBIDDEN(Lang, Txt)]}.
 
 filter_xmlels(Xmlels) -> filter_xmlels(Xmlels, []).
 
diff --git a/src/mod_proxy65_service.erl b/src/mod_proxy65_service.erl
index 8b4644ba..d64afa04 100644
--- a/src/mod_proxy65_service.erl
+++ b/src/mod_proxy65_service.erl
@@ -150,7 +150,7 @@ process_iq(_,
 		      children = iq_vcard(Lang)}]};
 %% bytestreams info request
 process_iq(JID,
-	   #iq{type = get, sub_el = SubEl,
+	   #iq{type = get, sub_el = SubEl, lang = Lang,
 	       xmlns = ?NS_BYTESTREAMS} =
 	       IQ,
 	   #state{acl = ACL, stream_addr = StreamAddr,
@@ -165,11 +165,12 @@ process_iq(JID,
 			    attrs = [{<<"xmlns">>, ?NS_BYTESTREAMS}],
 			    children = StreamHostEl}]};
       deny ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_FORBIDDEN]}
+	  Txt = <<"Denied by ACL">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_FORBIDDEN(Lang, Txt)]}
     end;
 %% bytestream activation request
 process_iq(InitiatorJID,
-	   #iq{type = set, sub_el = SubEl,
+	   #iq{type = set, sub_el = SubEl, lang = Lang,
 	       xmlns = ?NS_BYTESTREAMS} =
 	       IQ,
 	   #state{acl = ACL, serverhost = ServerHost}) ->
@@ -194,22 +195,27 @@ process_iq(InitiatorJID,
 		    of
 		  ok -> IQ#iq{type = result, sub_el = []};
 		  false ->
+		      Txt = <<"Failed to activate bytestream">>,
 		      IQ#iq{type = error,
-			    sub_el = [SubEl, ?ERR_ITEM_NOT_FOUND]};
+			    sub_el = [SubEl, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)]};
 		  limit ->
+		      Txt = <<"Too many active bytestreams">>,
 		      IQ#iq{type = error,
-			    sub_el = [SubEl, ?ERR_RESOURCE_CONSTRAINT]};
+			    sub_el = [SubEl, ?ERRT_RESOURCE_CONSTRAINT(Lang, Txt)]};
 		  conflict ->
-		      IQ#iq{type = error, sub_el = [SubEl, ?ERR_CONFLICT]};
+		      Txt = <<"Bytestream already activated">>,
+		      IQ#iq{type = error, sub_el = [SubEl, ?ERRT_CONFLICT(Lang, Txt)]};
 		  _ ->
 		      IQ#iq{type = error,
 			    sub_el = [SubEl, ?ERR_INTERNAL_SERVER_ERROR]}
 		end;
 	    _ ->
-		IQ#iq{type = error, sub_el = [SubEl, ?ERR_BAD_REQUEST]}
+		Txt = <<"Malformed JID">>,
+		IQ#iq{type = error, sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt)]}
 	  end;
       deny ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_FORBIDDEN]}
+	  Txt = <<"Denied by ACL">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_FORBIDDEN(Lang, Txt)]}
     end;
 %% Unknown "set" or "get" request
 process_iq(_, #iq{type = Type, sub_el = SubEl} = IQ, _)
diff --git a/src/mod_pubsub.erl b/src/mod_pubsub.erl
index 6531ed87..247b9f8c 100644
--- a/src/mod_pubsub.erl
+++ b/src/mod_pubsub.erl
@@ -1034,7 +1034,10 @@ do_route(ServerHost, Access, Plugins, Host, From, To, Packet) ->
 				none ->
 				    ok;
 				invalid ->
-				    Err = jlib:make_error_reply(Packet, ?ERR_BAD_REQUEST),
+				    Lang = fxml:get_attr_s(<<"xml:lang">>, Attrs),
+				    Txt = <<"Incorrect authorization response">>,
+				    Err = jlib:make_error_reply(
+					    Packet, ?ERRT_BAD_REQUEST(Lang, Txt)),
 				    ejabberd_router:route(To, From, Err);
 				XFields ->
 				    handle_authorization_response(Host, From, To, Packet, XFields)
@@ -1418,13 +1421,14 @@ adhoc_request(Host, _ServerHost, Owner,
     send_pending_node_form(Host, Owner, Lang, Plugins);
 adhoc_request(Host, _ServerHost, Owner,
 	    #adhoc_request{node = ?NS_PUBSUB_GET_PENDING,
-		action = <<"execute">>, xdata = XData},
+		action = <<"execute">>, xdata = XData, lang = Lang},
 	    _Access, _Plugins) ->
     ParseOptions = case XData of
 	#xmlel{name = <<"x">>} = XEl ->
 	    case jlib:parse_xdata_submit(XEl) of
 		invalid ->
-		    {error, ?ERR_BAD_REQUEST};
+		    Txt = <<"Incorrect data form">>,
+		    {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 		XData2 ->
 		    case set_xoption(Host, XData2, []) of
 			NewOpts when is_list(NewOpts) -> {result, NewOpts};
@@ -1432,8 +1436,8 @@ adhoc_request(Host, _ServerHost, Owner,
 		    end
 	    end;
 	_ ->
-	    ?INFO_MSG("Bad XForm: ~p", [XData]),
-	    {error, ?ERR_BAD_REQUEST}
+	    Txt = <<"No data form found">>,
+	    {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
     end,
     case ParseOptions of
 	{result, XForm} ->
@@ -1463,7 +1467,9 @@ send_pending_node_form(Host, Owner, _Lang, Plugins) ->
     end,
     case lists:filter(Filter, Plugins) of
 	[] ->
-	    {error, ?ERR_FEATURE_NOT_IMPLEMENTED};
+	    Err = extended_error(?ERR_FEATURE_NOT_IMPLEMENTED,
+				 unsupported, <<"get-pending">>),
+	    {error, Err};
 	Ps ->
 	    XOpts = [#xmlel{name = <<"option">>, attrs = [],
 			children = [#xmlel{name = <<"value">>,
@@ -1504,10 +1510,11 @@ send_pending_auth_events(Host, Node, Owner) ->
 		true ->
 		    case node_call(Host, Type, get_affiliation, [Nidx, Owner]) of
 			{result, owner} -> node_call(Host, Type, get_node_subscriptions, [Nidx]);
-			_ -> {error, ?ERR_FORBIDDEN}
+			_ -> {error, ?ERRT_FORBIDDEN(?MYLANG, <<"You're not an owner">>)}
 		    end;
 		false ->
-		    {error, ?ERR_FEATURE_NOT_IMPLEMENTED}
+		    {error, extended_error(?ERR_FEATURE_NOT_IMPLEMENTED,
+					   unsupported, <<"get-pending">>)}
 	    end
     end,
     case transaction(Host, Node, Action, sync_dirty) of
@@ -1644,6 +1651,7 @@ send_authorization_approval(Host, JID, SNode, Subscription) ->
     ejabberd_router:route(service_jid(Host), JID, Stanza).
 
 handle_authorization_response(Host, From, To, Packet, XFields) ->
+    Lang = fxml:get_tag_attr_s(<<"xml:lang">>, Packet),
     case {lists:keysearch(<<"pubsub#node">>, 1, XFields),
 	    lists:keysearch(<<"pubsub#subscriber_jid">>, 1, XFields),
 	    lists:keysearch(<<"pubsub#allow">>, 1, XFields)}
@@ -1665,7 +1673,7 @@ handle_authorization_response(Host, From, To, Packet, XFields) ->
 			    {result, Subs} = node_call(Host, Type, get_subscriptions, [Nidx, Subscriber]),
 			    update_auth(Host, Node, Type, Nidx, Subscriber, Allow, Subs);
 			false ->
-			    {error, ?ERR_FORBIDDEN}
+			    {error, ?ERRT_FORBIDDEN(Lang, <<"You're not an owner">>)}
 		    end
 	    end,
 	    case transaction(Host, Node, Action, sync_dirty) of
@@ -1680,7 +1688,8 @@ handle_authorization_response(Host, From, To, Packet, XFields) ->
 		    ejabberd_router:route(To, From, Err)
 	    end;
 	_ ->
-	    Err = jlib:make_error_reply(Packet, ?ERR_NOT_ACCEPTABLE),
+	    Txt = <<"Incorrect data form">>,
+	    Err = jlib:make_error_reply(Packet, ?ERRT_NOT_ACCEPTABLE(Lang, Txt)),
 	    ejabberd_router:route(To, From, Err)
     end.
 
@@ -1691,7 +1700,7 @@ update_auth(Host, Node, Type, Nidx, Subscriber, Allow, Subs) ->
 	    end,
 	    Subs),
     case Sub of
-	[{pending, SubId}] ->
+	[{pending, SubId}|_] ->
 	    NewSub = case Allow of
 		true -> subscribed;
 		false -> none
@@ -1700,7 +1709,8 @@ update_auth(Host, Node, Type, Nidx, Subscriber, Allow, Subs) ->
 	    send_authorization_approval(Host, Subscriber, Node, NewSub),
 	    {result, ok};
 	_ ->
-	    {error, ?ERR_UNEXPECTED_REQUEST}
+	    Txt = <<"No pending subscriptions found">>,
+	    {error, ?ERRT_UNEXPECTED_REQUEST(?MYLANG, Txt)}
     end.
 
 -define(XFIELD(Type, Label, Var, Val),
@@ -1830,7 +1840,8 @@ create_node(Host, ServerHost, Node, Owner, GivenType, Access, Configuration) ->
 	[#xmlel{name = <<"x">>} = XEl] ->
 	    case jlib:parse_xdata_submit(XEl) of
 		invalid ->
-		    {error, ?ERR_BAD_REQUEST};
+		    Txt = <<"Incorrect data form">>,
+		    {error, ?ERRT_BAD_REQUEST(?MYLANG, Txt)};
 		XData ->
 		    case set_xoption(Host, XData, node_options(Host, Type)) of
 			NewOpts when is_list(NewOpts) -> {result, NewOpts};
@@ -1839,7 +1850,8 @@ create_node(Host, ServerHost, Node, Owner, GivenType, Access, Configuration) ->
 	    end;
 	_ ->
 	    ?INFO_MSG("Node ~p; bad configuration: ~p", [Node, Configuration]),
-	    {error, ?ERR_BAD_REQUEST}
+	    Txt = <<"No data form found">>,
+	    {error, ?ERRT_BAD_REQUEST(?MYLANG, Txt)}
     end,
     case ParseOptions of
 	{result, NodeOptions} ->
@@ -1876,7 +1888,8 @@ create_node(Host, ServerHost, Node, Owner, GivenType, Access, Configuration) ->
 				    Error
 			    end;
 			_ ->
-			    {error, ?ERR_FORBIDDEN}
+			    Txt1 = <<"You're not allowed to create nodes">>,
+			    {error, ?ERRT_FORBIDDEN(?MYLANG, Txt1)}
 		    end
 	    end,
 	    Reply = [#xmlel{name = <<"pubsub">>,
@@ -1926,7 +1939,7 @@ create_node(Host, ServerHost, Node, Owner, GivenType, Access, Configuration) ->
     | {error, xmlel()}
     ).
 delete_node(_Host, <<>>, _Owner) ->
-    {error, ?ERR_NOT_ALLOWED};
+    {error, ?ERRT_NOT_ALLOWED(?MYLANG, <<"No node specified">>)};
 delete_node(Host, Node, Owner) ->
     Action = fun (#pubsub_node{type = Type, id = Nidx}) ->
 	    case node_call(Host, Type, get_affiliation, [Nidx, Owner]) of
@@ -1938,7 +1951,7 @@ delete_node(Host, Node, Owner) ->
 			Error -> Error
 		    end;
 		_ ->
-		    {error, ?ERR_FORBIDDEN}
+		    {error, ?ERRT_FORBIDDEN(?MYLANG, <<"You're not an owner">>)}
 	    end
     end,
     Reply = [],
@@ -2247,22 +2260,28 @@ publish_item(Host, ServerHost, Node, Publisher, ItemId, Payload, Access) ->
 	    {result, Reply};
 	{result, {_, Result}} ->
 	    {result, Result};
-	{error, ?ERR_ITEM_NOT_FOUND} ->
-	    Type = select_type(ServerHost, Host, Node),
-	    case lists:member(<<"auto-create">>, plugin_features(Host, Type)) of
+	{error, _} = Error ->
+	    case is_item_not_found(Error) of
 		true ->
-		    case create_node(Host, ServerHost, Node, Publisher, Type, Access, []) of
-			{result,
-				    [#xmlel{name = <<"pubsub">>,
-					    attrs = [{<<"xmlns">>, ?NS_PUBSUB}],
-					    children = [#xmlel{name = <<"create">>,
-						    attrs = [{<<"node">>, NewNode}]}]}]} ->
-			    publish_item(Host, ServerHost, NewNode, Publisher, ItemId, Payload);
-			_ ->
-			    {error, ?ERR_ITEM_NOT_FOUND}
+		    Type = select_type(ServerHost, Host, Node),
+		    case lists:member(<<"auto-create">>, plugin_features(Host, Type)) of
+			true ->
+			    case create_node(Host, ServerHost, Node, Publisher, Type, Access, []) of
+				{result,
+				 [#xmlel{name = <<"pubsub">>,
+					 attrs = [{<<"xmlns">>, ?NS_PUBSUB}],
+					 children = [#xmlel{name = <<"create">>,
+							    attrs = [{<<"node">>, NewNode}]}]}]} ->
+				    publish_item(Host, ServerHost, NewNode, Publisher, ItemId, Payload);
+				_ ->
+				    {error, ?ERR_ITEM_NOT_FOUND}
+			    end;
+			false ->
+			    Txt = <<"Automatic node creation is not enabled">>,
+			    {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, Txt)}
 		    end;
 		false ->
-		    {error, ?ERR_ITEM_NOT_FOUND}
+		    Error
 	    end;
 	Error ->
 	    Error
@@ -2416,7 +2435,9 @@ get_items(Host, Node, From, SubId, SMaxItems, ItemIds, RSM) ->
 	    end;
 	true ->
 	    case catch jlib:binary_to_integer(SMaxItems) of
-		{'EXIT', _} -> {error, ?ERR_BAD_REQUEST};
+		{'EXIT', _} ->
+		    Txt = <<"Value of 'max_items' should be integer">>,
+		    {error, ?ERRT_BAD_REQUEST(?MYLANG, Txt)};
 		Val -> Val
 	    end
     end,
@@ -2639,7 +2660,7 @@ get_affiliations(Host, Node, JID) ->
 		    {error,
 			extended_error(?ERR_FEATURE_NOT_IMPLEMENTED, unsupported, <<"modify-affiliations">>)};
 		Affiliation /= owner ->
-		    {error, ?ERR_FORBIDDEN};
+		    {error, ?ERRT_FORBIDDEN(?MYLANG, <<"You're not an owner">>)};
 		true ->
 		    node_call(Host, Type, get_node_affiliations, [Nidx])
 	    end
@@ -2732,7 +2753,7 @@ set_affiliations(Host, Node, From, EntitiesEls) ->
 				FilteredEntities),
 			    {result, []};
 			_ ->
-			    {error, ?ERR_FORBIDDEN}
+			    {error, ?ERRT_FORBIDDEN(?MYLANG, <<"You're not an owner">>)}
 		    end
 	    end,
 	    case transaction(Host, Node, Action, sync_dirty) of
@@ -2948,7 +2969,7 @@ get_subscriptions(Host, Node, JID) ->
 		    {error,
 			extended_error(?ERR_FEATURE_NOT_IMPLEMENTED, unsupported, <<"manage-subscriptions">>)};
 		Affiliation /= owner ->
-		    {error, ?ERR_FORBIDDEN};
+		    {error, ?ERRT_FORBIDDEN(?MYLANG, <<"You're not an owner">>)};
 		true ->
 		    node_call(Host, Type, get_node_subscriptions, [Nidx])
 	    end
@@ -3059,10 +3080,10 @@ set_subscriptions(Host, Node, From, EntitiesEls) ->
 				    [], Entities),
 			    case Result of
 				[] -> {result, []};
-				_ -> {error, ?ERR_NOT_ACCEPTABLE}
+				[{error, E}|_] -> {error, E}
 			    end;
 			_ ->
-			    {error, ?ERR_FORBIDDEN}
+			    {error, ?ERRT_FORBIDDEN(?MYLANG, <<"You're not an owner">>)}
 		    end
 	    end,
 	    case transaction(Host, Node, Action, sync_dirty) of
@@ -3606,7 +3627,7 @@ get_configure(Host, ServerHost, Node, From, Lang) ->
 						children =
 						get_configure_xfields(Type, Options, Lang, Groups)}]}]}]};
 		_ ->
-		    {error, ?ERR_FORBIDDEN}
+		    {error, ?ERRT_FORBIDDEN(Lang, <<"You're not an owner">>)}
 	    end
     end,
     case transaction(Host, Node, Action, sync_dirty) of
@@ -3820,7 +3841,8 @@ set_configure(Host, Node, From, Els, Lang) ->
 				{result, owner} ->
 				    case jlib:parse_xdata_submit(XEl) of
 					invalid ->
-					    {error, ?ERR_BAD_REQUEST};
+					    Txt = <<"Incorrect data form">>,
+					    {error, ?ERRT_BAD_REQUEST(Lang, Txt)};
 					XData ->
 					    OldOpts = case Options of
 						[] -> node_options(Host, Type);
@@ -3840,7 +3862,8 @@ set_configure(Host, Node, From, Els, Lang) ->
 					    end
 				    end;
 				_ ->
-				    {error, ?ERR_FORBIDDEN}
+				    Txt = <<"You're not an owner">>,
+				    {error, ?ERRT_FORBIDDEN(Lang, Txt)}
 			    end
 		    end,
 		    case transaction(Host, Node, Action, transaction) of
@@ -3854,10 +3877,12 @@ set_configure(Host, Node, From, Els, Lang) ->
 			    Other
 		    end;
 		_ ->
-		    {error, ?ERR_BAD_REQUEST}
+		    Txt = <<"Incorrect data form">>,
+		    {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
 	    end;
 	_ ->
-	    {error, ?ERR_BAD_REQUEST}
+	    Txt = <<"No data form found">>,
+	    {error, ?ERRT_BAD_REQUEST(Lang, Txt)}
     end.
 
 add_opt(Key, Value, Opts) ->
@@ -3872,7 +3897,10 @@ add_opt(Key, Value, Opts) ->
 	_ -> error
     end,
     case BoolVal of
-	error -> {error, ?ERR_NOT_ACCEPTABLE};
+	error ->
+	    Txt = <<"Value of '~s' should be boolean">>,
+	    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)};
 	_ -> set_xoption(Host, Opts, add_opt(Opt, BoolVal, NewOpts))
     end).
 
@@ -3885,10 +3913,14 @@ add_opt(Key, Value, Opts) ->
 	    if (Max =:= undefined) orelse (IVal =< Max) ->
 		set_xoption(Host, Opts, add_opt(Opt, IVal, NewOpts));
 	       true ->
-		{error, ?ERR_NOT_ACCEPTABLE}
+		Txt = <<"Incorrect value of '~s'">>,
+		ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+		{error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}
 	    end;
 	_ ->
-	    {error, ?ERR_NOT_ACCEPTABLE}
+	    Txt = <<"Value of '~s' should be integer">>,
+	    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}
     end).
 
 -define(SET_ALIST_XOPT(Opt, Val, Vals),
@@ -3896,7 +3928,9 @@ add_opt(Key, Value, Opts) ->
 	true ->
 	    set_xoption(Host, Opts, add_opt(Opt, jlib:binary_to_atom(Val), NewOpts));
 	false ->
-	    {error, ?ERR_NOT_ACCEPTABLE}
+	    Txt = <<"Incorrect value of '~s'">>,
+	    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}
     end).
 
 -define(SET_LIST_XOPT(Opt, Val),
@@ -4139,8 +4173,9 @@ features(Host, Node) when is_binary(Node) ->
 tree_call({_User, Server, _Resource}, Function, Args) ->
     tree_call(Server, Function, Args);
 tree_call(Host, Function, Args) ->
-    ?DEBUG("tree_call ~p ~p ~p", [Host, Function, Args]),
-    catch apply(tree(Host), Function, Args).
+    Tree = tree(Host),
+    ?DEBUG("tree_call apply(~s, ~s, ~p) @ ~s", [Tree, Function, Args, Host]),
+    catch apply(Tree, Function, Args).
 
 tree_action(Host, Function, Args) ->
     ?DEBUG("tree_action ~p ~p ~p", [Host, Function, Args]),
@@ -4267,6 +4302,13 @@ extended_error(#xmlel{name = Error, attrs = Attrs, children = SubEls}, Ext, ExtA
     #xmlel{name = Error, attrs = Attrs,
 	children = lists:reverse([#xmlel{name = Ext, attrs = ExtAttrs} | SubEls])}.
 
+is_item_not_found({error, ErrEl}) ->
+    case fxml:get_subtag_with_xmlns(
+	   ErrEl, <<"item-not-found">>, ?NS_STANZAS) of
+	#xmlel{} -> true;
+	_ -> false
+    end.
+
 string_to_ljid(JID) ->
     case jid:from_string(JID) of
 	error ->
diff --git a/src/mod_register.erl b/src/mod_register.erl
index 56c5f720..fee2a228 100644
--- a/src/mod_register.erl
+++ b/src/mod_register.erl
@@ -151,21 +151,28 @@ process_iq(From, To,
 				%% modules.  lists:foreach can
 				%% only return ok:
 				not_allowed ->
+				    Txt = <<"Removal is not allowed">>,
 				    IQ#iq{type = error,
-					  sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+					  sub_el = [SubEl,
+						    ?ERRT_NOT_ALLOWED(Lang, Txt)]};
 				not_exists ->
+				    Txt = <<"No such user">>,
 				    IQ#iq{type = error,
 					  sub_el =
-					      [SubEl, ?ERR_ITEM_NOT_FOUND]};
-				_ ->
+					      [SubEl,
+					       ?ERRT_ITEM_NOT_FOUND(Lang, Txt)]};
+				Err ->
+				    ?ERROR_MSG("failed to remove user ~s@~s: ~p",
+					       [User, Server, Err]),
 				    IQ#iq{type = error,
 					  sub_el =
 					      [SubEl,
 					       ?ERR_INTERNAL_SERVER_ERROR]}
 			      end;
 			  true ->
+			      Txt = <<"No password in this query">>,
 			      IQ#iq{type = error,
-				    sub_el = [SubEl, ?ERR_BAD_REQUEST]}
+				    sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt)]}
 		       end
 		 end;
 	     (UTag == false) and (RTag /= false) and AllowRemove ->
@@ -182,7 +189,9 @@ process_iq(From, To,
 		       ejabberd_auth:remove_user(User, Server),
 		       ignore;
 		   _ ->
-		       IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]}
+		       Txt = <<"The query is only allowed from local users">>,
+		       IQ#iq{type = error,
+			     sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]}
 		 end;
 	     (UTag /= false) and (PTag /= false) ->
 		 User = fxml:get_tag_cdata(UTag),
@@ -200,11 +209,14 @@ process_iq(From, To,
 							  SubEl, Source, Lang,
 							  true);
 			 _ ->
+			     Txt = <<"Incorrect data form">>,
 			     IQ#iq{type = error,
-				   sub_el = [SubEl, ?ERR_BAD_REQUEST]}
+				   sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt)]}
 		       end;
 		   {error, malformed} ->
-		       IQ#iq{type = error, sub_el = [SubEl, ?ERR_BAD_REQUEST]};
+		       Txt = <<"Incorrect CAPTCHA submit">>,
+		       IQ#iq{type = error,
+			     sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt)]};
 		   _ ->
 		       ErrText = <<"The CAPTCHA verification has failed">>,
 		       IQ#iq{type = error,
@@ -344,7 +356,8 @@ try_register_or_set_password(User, Server, Password,
 		      IQ#iq{type = error, sub_el = [SubEl, Error]}
 		end;
 	    deny ->
-		IQ#iq{type = error, sub_el = [SubEl, ?ERR_FORBIDDEN]}
+		Txt = <<"Denied by ACL">>,
+		IQ#iq{type = error, sub_el = [SubEl, ?ERRT_FORBIDDEN(Lang, Txt)]}
 	  end;
       _ ->
 	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]}
@@ -359,13 +372,17 @@ try_set_password(User, Server, Password, IQ, SubEl,
 	      of
 	    ok -> IQ#iq{type = result, sub_el = []};
 	    {error, empty_password} ->
-		IQ#iq{type = error, sub_el = [SubEl, ?ERR_BAD_REQUEST]};
+		Txt = <<"Empty password">>,
+		IQ#iq{type = error, sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt)]};
 	    {error, not_allowed} ->
-		IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+		Txt = <<"Chaning password is not allowed">>,
+		IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
 	    {error, invalid_jid} ->
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_ITEM_NOT_FOUND]};
-	    _ ->
+		      sub_el = [SubEl, ?ERR_JID_MALFORMED]};
+	    Err ->
+		?ERROR_MSG("failed to register user ~s@~s: ~p",
+			   [User, Server, Err]),
 		IQ#iq{type = error,
 		      sub_el = [SubEl, ?ERR_INTERNAL_SERVER_ERROR]}
 	  end;
@@ -377,7 +394,7 @@ try_set_password(User, Server, Password, IQ, SubEl,
 
 try_register(User, Server, Password, SourceRaw, Lang) ->
     case jid:is_nodename(User) of
-      false -> {error, ?ERR_BAD_REQUEST};
+      false -> {error, ?ERRT_BAD_REQUEST(Lang, <<"Malformed username">>)};
       _ ->
 	  JID = jid:make(User, Server, <<"">>),
 	  Access = gen_mod:get_module_opt(Server, ?MODULE, access,
@@ -387,8 +404,8 @@ try_register(User, Server, Password, SourceRaw, Lang) ->
 	  case {acl:match_rule(Server, Access, JID),
 		check_ip_access(SourceRaw, IPAccess)}
 	      of
-	    {deny, _} -> {error, ?ERR_FORBIDDEN};
-	    {_, deny} -> {error, ?ERR_FORBIDDEN};
+	    {deny, _} -> {error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
+	    {_, deny} -> {error, ?ERRT_FORBIDDEN(Lang, <<"Denied by ACL">>)};
 	    {allow, allow} ->
 		Source = may_remove_resource(SourceRaw),
 		case check_timeout(Source) of
@@ -406,14 +423,20 @@ try_register(User, Server, Password, SourceRaw, Lang) ->
 			      Error ->
 				  remove_timeout(Source),
 				  case Error of
-				    {atomic, exists} -> {error, ?ERR_CONFLICT};
+				    {atomic, exists} ->
+					Txt = <<"User already exists">>,
+					{error, ?ERRT_CONFLICT(Lang, Txt)};
 				    {error, invalid_jid} ->
 					{error, ?ERR_JID_MALFORMED};
 				    {error, not_allowed} ->
 					{error, ?ERR_NOT_ALLOWED};
 				    {error, too_many_users} ->
-					{error, ?ERR_NOT_ALLOWED};
-				    {error, _Reason} ->
+					Txt = <<"Too many users registered">>,
+					{error, ?ERRT_RESOURCE_CONSTRAINT(Lang, Txt)};
+				    {error, _} ->
+					?ERROR_MSG("failed to register user "
+						   "~s@~s: ~p",
+						   [User, Server, Error]),
 					{error, ?ERR_INTERNAL_SERVER_ERROR}
 				  end
 			    end;
diff --git a/src/mod_roster.erl b/src/mod_roster.erl
index 997544b1..35072e5f 100644
--- a/src/mod_roster.erl
+++ b/src/mod_roster.erl
@@ -137,13 +137,14 @@ process_iq(From, To, IQ) when ((From#jid.luser == <<"">>) andalso (From#jid.reso
     process_iq_manager(From, To, IQ);
 
 process_iq(From, To, IQ) ->
-    #iq{sub_el = SubEl} = IQ,
+    #iq{sub_el = SubEl, lang = Lang} = IQ,
     #jid{lserver = LServer} = From,
     case lists:member(LServer, ?MYHOSTS) of
       true -> process_local_iq(From, To, IQ);
       _ ->
+	  Txt = <<"The query is only allowed from local users">>,
 	  IQ#iq{type = error,
-		sub_el = [SubEl, ?ERR_ITEM_NOT_FOUND]}
+		sub_el = [SubEl, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)]}
     end.
 
 process_local_iq(From, To, #iq{type = Type} = IQ) ->
@@ -479,12 +480,13 @@ get_roster_by_jid_t(LUser, LServer, LJID, riak) ->
             exit(Err)
     end.
 
-try_process_iq_set(From, To, #iq{sub_el = SubEl} = IQ) ->
+try_process_iq_set(From, To, #iq{sub_el = SubEl, lang = Lang} = IQ) ->
     #jid{server = Server} = From,
     Access = gen_mod:get_module_opt(Server, ?MODULE, access, fun(A) when is_atom(A) -> A end, all),
     case acl:match_rule(Server, Access, From) of
 	deny ->
-	    IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	    Txt = <<"Denied by ACL">>,
+	    IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
 	allow ->
 	    process_iq_set(From, To, IQ)
     end.
@@ -1616,8 +1618,9 @@ process_iq_manager(From, To, IQ) ->
 	true ->
 	    process_iq_manager2(MatchDomain, To, IQ);
 	false ->
-	    #iq{sub_el = SubEl} = IQ,
-	    IQ#iq{type = error, sub_el = [SubEl, ?ERR_BAD_REQUEST]}
+	    #iq{sub_el = SubEl, lang = Lang} = IQ,
+	    Txt = <<"Roster management is not allowed from this domain">>,
+	    IQ#iq{type = error, sub_el = [SubEl, ?ERRT_BAD_REQUEST(Lang, Txt)]}
     end.
 
 process_iq_manager2(MatchDomain, To, IQ) ->
diff --git a/src/mod_sic.erl b/src/mod_sic.erl
index 3ffd9c91..b4eae0da 100644
--- a/src/mod_sic.erl
+++ b/src/mod_sic.erl
@@ -60,8 +60,9 @@ process_local_iq(#jid{user = User, server = Server,
 		 _To, #iq{type = get, sub_el = _SubEl} = IQ) ->
     get_ip({User, Server, Resource}, IQ);
 process_local_iq(_From, _To,
-		 #iq{type = set, sub_el = SubEl} = IQ) ->
-    IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]}.
+		 #iq{type = set, sub_el = SubEl, lang = Lang} = IQ) ->
+    Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+    IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]}.
 
 process_sm_iq(#jid{user = User, server = Server,
 		   resource = Resource},
@@ -69,14 +70,17 @@ process_sm_iq(#jid{user = User, server = Server,
 	      #iq{type = get, sub_el = _SubEl} = IQ) ->
     get_ip({User, Server, Resource}, IQ);
 process_sm_iq(_From, _To,
-	      #iq{type = get, sub_el = SubEl} = IQ) ->
-    IQ#iq{type = error, sub_el = [SubEl, ?ERR_FORBIDDEN]};
+	      #iq{type = get, sub_el = SubEl, lang = Lang} = IQ) ->
+    Txt = <<"Query to another users is forbidden">>,
+    IQ#iq{type = error, sub_el = [SubEl, ?ERRT_FORBIDDEN(Lang, Txt)]};
 process_sm_iq(_From, _To,
-	      #iq{type = set, sub_el = SubEl} = IQ) ->
-    IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]}.
+	      #iq{type = set, sub_el = SubEl, lang = Lang} = IQ) ->
+    Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+    IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]}.
 
 get_ip({User, Server, Resource},
-       #iq{sub_el =
+       #iq{lang = Lang,
+	   sub_el =
 	       #xmlel{name = Name, attrs = Attrs} = SubEl} =
 	   IQ) ->
     case ejabberd_sm:get_user_ip(User, Server, Resource) of
@@ -88,8 +92,9 @@ get_ip({User, Server, Resource},
 				[{xmlcdata,
 				  iolist_to_binary(jlib:ip_to_list(IP))}]}]};
       _ ->
+	  Txt = <<"User session not found">>,
 	  IQ#iq{type = error,
-		sub_el = [SubEl, ?ERR_INTERNAL_SERVER_ERROR]}
+		sub_el = [SubEl, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt)]}
     end.
 
 mod_opt_type(iqdisc) -> fun gen_iq_handler:check_type/1;
diff --git a/src/mod_stats.erl b/src/mod_stats.erl
index 0328aec3..c14cf8d1 100644
--- a/src/mod_stats.erl
+++ b/src/mod_stats.erl
@@ -50,17 +50,18 @@ stop(Host) ->
 
 process_local_iq(_From, To,
 		 #iq{id = _ID, type = Type, xmlns = XMLNS,
-		     sub_el = SubEl} =
+		     sub_el = SubEl, lang = Lang} =
 		     IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  #xmlel{children = Els} = SubEl,
 	  Node = str:tokens(fxml:get_tag_attr_s(<<"node">>, SubEl),
 			    <<"/">>),
 	  Names = get_names(Els, []),
-	  case get_local_stats(To#jid.server, Node, Names) of
+	  case get_local_stats(To#jid.server, Node, Names, Lang) of
 	    {result, Res} ->
 		IQ#iq{type = result,
 		      sub_el =
@@ -87,18 +88,18 @@ get_names([_ | Els], Res) -> get_names(Els, Res).
 	#xmlel{name = <<"stat">>, attrs = [{<<"name">>, Name}],
 	       children = []}).
 
-get_local_stats(_Server, [], []) ->
+get_local_stats(_Server, [], [], _Lang) ->
     {result,
      [?STAT(<<"users/online">>), ?STAT(<<"users/total">>),
       ?STAT(<<"users/all-hosts/online">>),
       ?STAT(<<"users/all-hosts/total">>)]};
-get_local_stats(Server, [], Names) ->
+get_local_stats(Server, [], Names, _Lang) ->
     {result,
      lists:map(fun (Name) -> get_local_stat(Server, [], Name)
 	       end,
 	       Names)};
 get_local_stats(_Server, [<<"running nodes">>, _],
-		[]) ->
+		[], _Lang) ->
     {result,
      [?STAT(<<"time/uptime">>), ?STAT(<<"time/cputime">>),
       ?STAT(<<"users/online">>),
@@ -107,16 +108,19 @@ get_local_stats(_Server, [<<"running nodes">>, _],
       ?STAT(<<"transactions/restarted">>),
       ?STAT(<<"transactions/logged">>)]};
 get_local_stats(_Server, [<<"running nodes">>, ENode],
-		Names) ->
+		Names, Lang) ->
     case search_running_node(ENode) of
-      false -> {error, ?ERR_ITEM_NOT_FOUND};
+      false ->
+	    Txt = <<"No running node found">>,
+	    {error, ?ERRT_ITEM_NOT_FOUND(Lang, Txt)};
       Node ->
 	  {result,
 	   lists:map(fun (Name) -> get_node_stat(Node, Name) end,
 		     Names)}
     end;
-get_local_stats(_Server, _, _) ->
-    {error, ?ERR_FEATURE_NOT_IMPLEMENTED}.
+get_local_stats(_Server, _, _, Lang) ->
+    Txt = <<"No statistics found for this item">>,
+    {error, ?ERRT_FEATURE_NOT_IMPLEMENTED(Lang, Txt)}.
 
 -define(STATVAL(Val, Unit),
 	#xmlel{name = <<"stat">>,
diff --git a/src/mod_time.erl b/src/mod_time.erl
index 8bfe9f9f..740b654a 100644
--- a/src/mod_time.erl
+++ b/src/mod_time.erl
@@ -51,10 +51,11 @@ stop(Host) ->
 				     ?NS_TIME).
 
 process_local_iq(_From, _To,
-		 #iq{type = Type, sub_el = SubEl} = IQ) ->
+		 #iq{type = Type, sub_el = SubEl, lang = Lang} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  Now_universal = calendar:universal_time(),
 	  Now_local = calendar:universal_time_to_local_time(Now_universal),
diff --git a/src/mod_vcard.erl b/src/mod_vcard.erl
index 256dc5de..4d7c80d5 100644
--- a/src/mod_vcard.erl
+++ b/src/mod_vcard.erl
@@ -152,7 +152,8 @@ process_local_iq(_From, _To,
 		 #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  IQ#iq{type = result,
 		sub_el =
@@ -176,7 +177,7 @@ process_local_iq(_From, _To,
     end.
 
 process_sm_iq(From, To,
-	      #iq{type = Type, sub_el = SubEl} = IQ) ->
+	      #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
 	  #jid{user = User, lserver = LServer} = From,
@@ -185,14 +186,16 @@ process_sm_iq(From, To,
 		set_vcard(User, LServer, SubEl),
 		IQ#iq{type = result, sub_el = []};
 	    false ->
-		IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]}
+		Txt = <<"The query is only allowed from local users">>,
+		IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]}
 	  end;
       get ->
 	  #jid{luser = LUser, lserver = LServer} = To,
 	  case get_vcard(LUser, LServer) of
 	    error ->
+		Txt = <<"Database failure">>,
 		IQ#iq{type = error,
-		      sub_el = [SubEl, ?ERR_INTERNAL_SERVER_ERROR]};
+		      sub_el = [SubEl, ?ERRT_INTERNAL_SERVER_ERROR(Lang, Txt)]};
 	    [] ->
 		IQ#iq{type = result,
 		      sub_el = [#xmlel{name = <<"vCard">>,
@@ -422,15 +425,17 @@ do_route(ServerHost, From, To, Packet) ->
 		       XDataEl = find_xdata_el(SubEl),
 		       case XDataEl of
 			 false ->
-			     Err = jlib:make_error_reply(Packet,
-							 ?ERR_BAD_REQUEST),
+			     Txt = <<"Data form not found">>,
+			     Err = jlib:make_error_reply(
+				     Packet, ?ERRT_BAD_REQUEST(Lang, Txt)),
 			     ejabberd_router:route(To, From, Err);
 			 _ ->
 			     XData = jlib:parse_xdata_submit(XDataEl),
 			     case XData of
 			       invalid ->
-				   Err = jlib:make_error_reply(Packet,
-							       ?ERR_BAD_REQUEST),
+				   Txt = <<"Incorrect data form">>,
+				   Err = jlib:make_error_reply(
+					   Packet, ?ERRT_BAD_REQUEST(Lang, Txt)),
 				   ejabberd_router:route(To, From, Err);
 			       _ ->
 				   ResIQ = IQ#iq{type = result,
@@ -470,7 +475,8 @@ do_route(ServerHost, From, To, Packet) ->
 	     #iq{type = Type, xmlns = ?NS_DISCO_INFO, lang = Lang} ->
 		 case Type of
 		   set ->
-		       Err = jlib:make_error_reply(Packet, ?ERR_NOT_ALLOWED),
+		       Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+		       Err = jlib:make_error_reply(Packet, ?ERRT_NOT_ALLOWED(Lang, Txt)),
 		       ejabberd_router:route(To, From, Err);
 		   get ->
 		       Info = ejabberd_hooks:run_fold(disco_info, ServerHost,
@@ -516,10 +522,11 @@ do_route(ServerHost, From, To, Packet) ->
 						       ++ Info}]},
 		       ejabberd_router:route(To, From, jlib:iq_to_xml(ResIQ))
 		 end;
-	     #iq{type = Type, xmlns = ?NS_DISCO_ITEMS} ->
+	     #iq{type = Type, lang = Lang, xmlns = ?NS_DISCO_ITEMS} ->
 		 case Type of
 		   set ->
-		       Err = jlib:make_error_reply(Packet, ?ERR_NOT_ALLOWED),
+		       Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+		       Err = jlib:make_error_reply(Packet, ?ERRT_NOT_ALLOWED(Lang, Txt)),
 		       ejabberd_router:route(To, From, Err);
 		   get ->
 		       ResIQ = IQ#iq{type = result,
diff --git a/src/mod_vcard_ldap.erl b/src/mod_vcard_ldap.erl
index 98aaf936..46f81af0 100644
--- a/src/mod_vcard_ldap.erl
+++ b/src/mod_vcard_ldap.erl
@@ -206,7 +206,8 @@ process_local_iq(_From, _To,
 		 #iq{type = Type, lang = Lang, sub_el = SubEl} = IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  IQ#iq{type = result,
 		sub_el =
@@ -240,10 +241,11 @@ process_sm_iq(_From, #jid{lserver = LServer} = To,
 
 process_vcard_ldap(To, IQ, Server) ->
     {ok, State} = eldap_utils:get_state(Server, ?PROCNAME),
-    #iq{type = Type, sub_el = SubEl} = IQ,
+    #iq{type = Type, sub_el = SubEl, lang = Lang} = IQ,
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  #jid{luser = LUser} = To,
 	  LServer = State#state.serverhost,
@@ -455,15 +457,17 @@ route(State, From, To, Packet) ->
 		       XDataEl = find_xdata_el(SubEl),
 		       case XDataEl of
 			 false ->
-			     Err = jlib:make_error_reply(Packet,
-							 ?ERR_BAD_REQUEST),
+			     Txt = <<"Data form not found">>,
+			     Err = jlib:make_error_reply(
+				     Packet, ?ERRT_BAD_REQUEST(Lang, Txt)),
 			     ejabberd_router:route(To, From, Err);
 			 _ ->
 			     XData = jlib:parse_xdata_submit(XDataEl),
 			     case XData of
 			       invalid ->
-				   Err = jlib:make_error_reply(Packet,
-							       ?ERR_BAD_REQUEST),
+				   Txt = <<"Incorrect data form">>,
+				   Err = jlib:make_error_reply(
+					   Packet, ?ERRT_BAD_REQUEST(Lang, Txt)),
 				   ejabberd_router:route(To, From, Err);
 			       _ ->
 				   ResIQ = IQ#iq{type = result,
@@ -505,7 +509,8 @@ route(State, From, To, Packet) ->
 	     #iq{type = Type, xmlns = ?NS_DISCO_INFO, lang = Lang} ->
 		 case Type of
 		   set ->
-		       Err = jlib:make_error_reply(Packet, ?ERR_NOT_ALLOWED),
+		       Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+		       Err = jlib:make_error_reply(Packet, ?ERRT_NOT_ALLOWED(Lang, Txt)),
 		       ejabberd_router:route(To, From, Err);
 		   get ->
 		       Info = ejabberd_hooks:run_fold(disco_info, ServerHost,
@@ -545,10 +550,11 @@ route(State, From, To, Packet) ->
 						       ++ Info}]},
 		       ejabberd_router:route(To, From, jlib:iq_to_xml(ResIQ))
 		 end;
-	     #iq{type = Type, xmlns = ?NS_DISCO_ITEMS} ->
+	     #iq{type = Type, lang = Lang, xmlns = ?NS_DISCO_ITEMS} ->
 		 case Type of
 		   set ->
-		       Err = jlib:make_error_reply(Packet, ?ERR_NOT_ALLOWED),
+		       Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+		       Err = jlib:make_error_reply(Packet, ?ERRT_NOT_ALLOWED(Lang, Txt)),
 		       ejabberd_router:route(To, From, Err);
 		   get ->
 		       ResIQ = IQ#iq{type = result,
diff --git a/src/mod_version.erl b/src/mod_version.erl
index 0e3b96bd..7f7759f2 100644
--- a/src/mod_version.erl
+++ b/src/mod_version.erl
@@ -52,11 +52,12 @@ stop(Host) ->
 
 process_local_iq(_From, To,
 		 #iq{id = _ID, type = Type, xmlns = _XMLNS,
-		     sub_el = SubEl} =
+		     sub_el = SubEl, lang = Lang} =
 		     IQ) ->
     case Type of
       set ->
-	  IQ#iq{type = error, sub_el = [SubEl, ?ERR_NOT_ALLOWED]};
+	  Txt = <<"Value 'set' of 'type' attribute is not allowed">>,
+	  IQ#iq{type = error, sub_el = [SubEl, ?ERRT_NOT_ALLOWED(Lang, Txt)]};
       get ->
 	  Host = To#jid.lserver,
 	  OS = case gen_mod:get_module_opt(Host, ?MODULE, show_os,
diff --git a/src/node_dag.erl b/src/node_dag.erl
index cbb8e18c..09ee85f9 100644
--- a/src/node_dag.erl
+++ b/src/node_dag.erl
@@ -77,8 +77,9 @@ publish_item(Nidx, Publisher, Model, MaxItems, ItemId, Payload) ->
 	#pubsub_node{options = Options} ->
 	    case find_opt(node_type, Options) of
 		collection ->
+		    Txt = <<"Publishing items to collection node is not allowed">>,
 		    {error,
-			?ERR_EXTENDED((?ERR_NOT_ALLOWED), <<"publish">>)};
+		     ?ERR_EXTENDED(?ERRT_NOT_ALLOWED(?MYLANG, Txt), <<"publish">>)};
 		_ ->
 		    node_hometree:publish_item(Nidx, Publisher, Model,
 			MaxItems, ItemId, Payload)
diff --git a/src/node_flat_odbc.erl b/src/node_flat_odbc.erl
index 5aeb973d..5dd52066 100644
--- a/src/node_flat_odbc.erl
+++ b/src/node_flat_odbc.erl
@@ -800,8 +800,10 @@ get_item(Nidx, ItemId) ->
 	{selected,
 		    [<<"itemid">>, <<"publisher">>, <<"creation">>, <<"modification">>, <<"payload">>], [RItem]} ->
 	    {result, raw_to_item(Nidx, RItem)};
-	_ ->
-	    {error, ?ERR_ITEM_NOT_FOUND}
+	{selected, _, []} ->
+	    {error, ?ERR_ITEM_NOT_FOUND};
+	{'EXIT', _} ->
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(?MYLANG, <<"Database failure">>)}
     end.
 
 get_item(Nidx, ItemId, JID, AccessModel, PresenceSubscription, RosterGroup, _SubId) ->
diff --git a/src/nodetree_dag.erl b/src/nodetree_dag.erl
index 8ac56b27..a105db83 100644
--- a/src/nodetree_dag.erl
+++ b/src/nodetree_dag.erl
@@ -69,13 +69,13 @@ create_node(Key, Node, Type, Owner, Options, Parents) ->
 		Other -> Other
 	    end;
 	_ ->
-	    {error, ?ERR_CONFLICT}
+	    {error, ?ERRT_CONFLICT(?MYLANG, <<"Node already exists">>)}
     end.
 
 delete_node(Key, Node) ->
     case find_node(Key, Node) of
 	false ->
-	    {error, ?ERR_ITEM_NOT_FOUND};
+	    {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)};
 	Record ->
 	    lists:foreach(fun (#pubsub_node{options = Opts} = Child) ->
 			NewOpts = remove_config_parent(Node, Opts),
@@ -99,7 +99,7 @@ get_node(Host, Node, _From) ->
 
 get_node(Host, Node) ->
     case find_node(Host, Node) of
-	false -> {error, ?ERR_ITEM_NOT_FOUND};
+	false -> {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)};
 	Record -> Record
     end.
 
@@ -115,7 +115,7 @@ get_nodes(Key) ->
 get_parentnodes(Host, Node, _From) ->
     case find_node(Host, Node) of
 	false ->
-	    {error, ?ERR_ITEM_NOT_FOUND};
+	    {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)};
 	#pubsub_node{parents = Parents} ->
 	    Q = qlc:q([N
 			|| #pubsub_node{nodeid = {NHost, NNode}} = N
@@ -139,7 +139,7 @@ get_subnodes(Host, <<>>) ->
     get_subnodes_helper(Host, <<>>);
 get_subnodes(Host, Node) ->
     case find_node(Host, Node) of
-	false -> {error, ?ERR_ITEM_NOT_FOUND};
+	false -> {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)};
 	_ -> get_subnodes_helper(Host, Node)
     end.
 
@@ -238,7 +238,7 @@ validate_parentage(Key, Owners, [<<>> | T]) ->
 validate_parentage(Key, Owners, [ParentID | T]) ->
     case find_node(Key, ParentID) of
 	false ->
-	    {error, ?ERR_ITEM_NOT_FOUND};
+	    {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)};
 	#pubsub_node{owners = POwners, options = POptions} ->
 	    NodeType = find_opt(node_type, ?DEFAULT_NODETYPE, POptions),
 	    MutualOwners = [O || O <- Owners, PO <- POwners, O == PO],
diff --git a/src/nodetree_tree.erl b/src/nodetree_tree.erl
index e3f7e251..ff8e3f64 100644
--- a/src/nodetree_tree.erl
+++ b/src/nodetree_tree.erl
@@ -74,15 +74,15 @@ get_node(Host, Node, _From) ->
     get_node(Host, Node).
 
 get_node(Host, Node) ->
-    case catch mnesia:read({pubsub_node, {Host, Node}}) of
+    case mnesia:read({pubsub_node, {Host, Node}}) of
 	[Record] when is_record(Record, pubsub_node) -> Record;
-	_ -> {error, ?ERR_ITEM_NOT_FOUND}
+	_ -> {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)}
     end.
 
 get_node(Nidx) ->
-    case catch mnesia:index_read(pubsub_node, Nidx, #pubsub_node.id) of
+    case mnesia:index_read(pubsub_node, Nidx, #pubsub_node.id) of
 	[Record] when is_record(Record, pubsub_node) -> Record;
-	_ -> {error, ?ERR_ITEM_NOT_FOUND}
+	_ -> {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)}
     end.
 
 get_nodes(Host, _From) ->
@@ -147,7 +147,7 @@ get_subnodes_tree(Host, Node) ->
 
 create_node(Host, Node, Type, Owner, Options, Parents) ->
     BJID = jid:tolower(jid:remove_resource(Owner)),
-    case catch mnesia:read({pubsub_node, {Host, Node}}) of
+    case mnesia:read({pubsub_node, {Host, Node}}) of
 	[] ->
 	    ParentExists = case Host of
 		{_U, _S, _R} ->
@@ -183,7 +183,7 @@ create_node(Host, Node, Type, Owner, Options, Parents) ->
 		    {error, ?ERR_FORBIDDEN}
 	    end;
 	_ ->
-	    {error, ?ERR_CONFLICT}
+	    {error, ?ERRT_CONFLICT(?MYLANG, <<"Node already exists">>)}
     end.
 
 delete_node(Host, Node) ->
diff --git a/src/nodetree_tree_odbc.erl b/src/nodetree_tree_odbc.erl
index ef1c20b6..6c139ad6 100644
--- a/src/nodetree_tree_odbc.erl
+++ b/src/nodetree_tree_odbc.erl
@@ -93,7 +93,8 @@ set_node(Record) when is_record(Record, pubsub_node) ->
     end,
     case Nidx of
 	none ->
-	    {error, ?ERR_INTERNAL_SERVER_ERROR};
+	    Txt = <<"Node index not found">>,
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(?MYLANG, Txt)};
 	_ ->
 	    lists:foreach(fun ({Key, Value}) ->
 			SKey = iolist_to_binary(atom_to_list(Key)),
@@ -125,9 +126,9 @@ get_node(Host, Node) ->
 		    [<<"node">>, <<"parent">>, <<"type">>, <<"nodeid">>], [RItem]} ->
 	    raw_to_node(Host, RItem);
 	{'EXIT', _Reason} ->
-	    {error, ?ERR_INTERNAL_SERVER_ERROR};
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(?MYLANG, <<"Database failure">>)};
 	_ ->
-	    {error, ?ERR_ITEM_NOT_FOUND}
+	    {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)}
     end.
 
 get_node(Nidx) ->
@@ -140,9 +141,9 @@ get_node(Nidx) ->
 		    [<<"host">>, <<"node">>, <<"parent">>, <<"type">>], [[Host, Node, Parent, Type]]} ->
 	    raw_to_node(Host, [Node, Parent, Type, Nidx]);
 	{'EXIT', _Reason} ->
-	    {error, ?ERR_INTERNAL_SERVER_ERROR};
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(?MYLANG, <<"Database failure">>)};
 	_ ->
-	    {error, ?ERR_ITEM_NOT_FOUND}
+	    {error, ?ERRT_ITEM_NOT_FOUND(?MYLANG, <<"Node not found">>)}
     end.
 
 get_nodes(Host, _From) ->
@@ -211,7 +212,7 @@ get_subnodes_tree(Host, Node) ->
 create_node(Host, Node, Type, Owner, Options, Parents) ->
     BJID = jid:tolower(jid:remove_resource(Owner)),
     case nodeidx(Host, Node) of
-	{error, ?ERR_ITEM_NOT_FOUND} ->
+	{error, not_found} ->
 	    ParentExists = case Host of
 		{_U, _S, _R} ->
 		    %% This is special case for PEP handling
@@ -248,9 +249,9 @@ create_node(Host, Node, Type, Owner, Options, Parents) ->
 		    {error, ?ERR_FORBIDDEN}
 	    end;
 	{result, _} ->
-	    {error, ?ERR_CONFLICT};
-	Error ->
-	    Error
+	    {error, ?ERRT_CONFLICT(?MYLANG, <<"Node already exists">>)};
+	{error, db_fail} ->
+	    {error, ?ERRT_INTERNAL_SERVER_ERROR(?MYLANG, <<"Database failure">>)}
     end.
 
 delete_node(Host, Node) ->
@@ -303,9 +304,9 @@ nodeidx(Host, Node) ->
 	{selected, [<<"nodeid">>], [[Nidx]]} ->
 	    {result, Nidx};
 	{'EXIT', _Reason} ->
-	    {error, ?ERR_INTERNAL_SERVER_ERROR};
+	    {error, db_fail};
 	_ ->
-	    {error, ?ERR_ITEM_NOT_FOUND}
+	    {error, not_found}
     end.
 
 nodeowners(Nidx) ->
diff --git a/src/pubsub_subscription.erl b/src/pubsub_subscription.erl
index 22c90414..f990f6e3 100644
--- a/src/pubsub_subscription.erl
+++ b/src/pubsub_subscription.erl
@@ -237,31 +237,40 @@ var_xfield(?PUBSUB_SUBSCRIPTION_TYPE) -> subscription_type;
 var_xfield(?PUBSUB_SUBSCRIPTION_DEPTH) -> subscription_depth;
 var_xfield(_) -> {error, badarg}.
 
-val_xfield(deliver, [Val]) -> xopt_to_bool(Val);
-val_xfield(digest, [Val]) -> xopt_to_bool(Val);
-val_xfield(digest_frequency, [Val]) ->
+val_xfield(deliver = Opt, [Val]) -> xopt_to_bool(Opt, Val);
+val_xfield(digest = Opt, [Val]) -> xopt_to_bool(Opt, Val);
+val_xfield(digest_frequency = Opt, [Val]) ->
     case catch jlib:binary_to_integer(Val) of
 	N when is_integer(N) -> N;
-	_ -> {error, ?ERR_NOT_ACCEPTABLE}
+	_ ->
+	    Txt = <<"Value of '~s' should be integer">>,
+	    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}
     end;
 val_xfield(expire, [Val]) -> jlib:datetime_string_to_timestamp(Val);
-val_xfield(include_body, [Val]) -> xopt_to_bool(Val);
+val_xfield(include_body = Opt, [Val]) -> xopt_to_bool(Opt, Val);
 val_xfield(show_values, Vals) -> Vals;
 val_xfield(subscription_type, [<<"items">>]) -> items;
 val_xfield(subscription_type, [<<"nodes">>]) -> nodes;
 val_xfield(subscription_depth, [<<"all">>]) -> all;
-val_xfield(subscription_depth, [Depth]) ->
+val_xfield(subscription_depth = Opt, [Depth]) ->
     case catch jlib:binary_to_integer(Depth) of
 	N when is_integer(N) -> N;
-	_ -> {error, ?ERR_NOT_ACCEPTABLE}
+	_ ->
+	    Txt = <<"Value of '~s' should be integer">>,
+	    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}
     end.
 
 %% Convert XForm booleans to Erlang booleans.
-xopt_to_bool(<<"0">>) -> false;
-xopt_to_bool(<<"1">>) -> true;
-xopt_to_bool(<<"false">>) -> false;
-xopt_to_bool(<<"true">>) -> true;
-xopt_to_bool(_) -> {error, ?ERR_NOT_ACCEPTABLE}.
+xopt_to_bool(_, <<"0">>) -> false;
+xopt_to_bool(_, <<"1">>) -> true;
+xopt_to_bool(_, <<"false">>) -> false;
+xopt_to_bool(_, <<"true">>) -> true;
+xopt_to_bool(Option, _) ->
+    Txt = <<"Value of '~s' should be boolean">>,
+    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Option])),
+    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}.
 
 -spec(get_option_xfield/3 ::
     (
diff --git a/src/pubsub_subscription_odbc.erl b/src/pubsub_subscription_odbc.erl
index 149308ad..afd31c81 100644
--- a/src/pubsub_subscription_odbc.erl
+++ b/src/pubsub_subscription_odbc.erl
@@ -200,31 +200,40 @@ var_xfield(?PUBSUB_SUBSCRIPTION_TYPE) -> subscription_type;
 var_xfield(?PUBSUB_SUBSCRIPTION_DEPTH) -> subscription_depth;
 var_xfield(_) -> {error, badarg}.
 
-val_xfield(deliver, [Val]) -> xopt_to_bool(Val);
-val_xfield(digest, [Val]) -> xopt_to_bool(Val);
-val_xfield(digest_frequency, [Val]) ->
+val_xfield(deliver = Opt, [Val]) -> xopt_to_bool(Opt, Val);
+val_xfield(digest = Opt, [Val]) -> xopt_to_bool(Opt, Val);
+val_xfield(digest_frequency = Opt, [Val]) ->
     case catch jlib:binary_to_integer(Val) of
 	N when is_integer(N) -> N;
-	_ -> {error, ?ERR_NOT_ACCEPTABLE}
+	_ ->
+	    Txt = <<"Value of '~s' should be integer">>,
+	    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}
     end;
 val_xfield(expire, [Val]) -> jlib:datetime_string_to_timestamp(Val);
-val_xfield(include_body, [Val]) -> xopt_to_bool(Val);
+val_xfield(include_body = Opt, [Val]) -> xopt_to_bool(Opt, Val);
 val_xfield(show_values, Vals) -> Vals;
 val_xfield(subscription_type, [<<"items">>]) -> items;
 val_xfield(subscription_type, [<<"nodes">>]) -> nodes;
 val_xfield(subscription_depth, [<<"all">>]) -> all;
-val_xfield(subscription_depth, [Depth]) ->
+val_xfield(subscription_depth = Opt, [Depth]) ->
     case catch jlib:binary_to_integer(Depth) of
 	N when is_integer(N) -> N;
-	_ -> {error, ?ERR_NOT_ACCEPTABLE}
+	_ ->
+	    Txt = <<"Value of '~s' should be integer">>,
+	    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Opt])),
+	    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}
     end.
 
 %% Convert XForm booleans to Erlang booleans.
-xopt_to_bool(<<"0">>) -> false;
-xopt_to_bool(<<"1">>) -> true;
-xopt_to_bool(<<"false">>) -> false;
-xopt_to_bool(<<"true">>) -> true;
-xopt_to_bool(_) -> {error, ?ERR_NOT_ACCEPTABLE}.
+xopt_to_bool(_, <<"0">>) -> false;
+xopt_to_bool(_, <<"1">>) -> true;
+xopt_to_bool(_, <<"false">>) -> false;
+xopt_to_bool(_, <<"true">>) -> true;
+xopt_to_bool(Option, _) ->
+    Txt = <<"Value of '~s' should be boolean">>,
+    ErrTxt = iolist_to_binary(io_lib:format(Txt, [Option])),
+    {error, ?ERRT_NOT_ACCEPTABLE(?MYLANG, ErrTxt)}.
 
 %% Return a field for an XForm for Key, with data filled in, if
 %% applicable, from Options.