diff --git a/packages/fcl-web/src/webdata/extjsjson.pp b/packages/fcl-web/src/webdata/extjsjson.pp
index 4525d74037..22daedb7c3 100644
--- a/packages/fcl-web/src/webdata/extjsjson.pp
+++ b/packages/fcl-web/src/webdata/extjsjson.pp
@@ -26,12 +26,15 @@ type
 
   { TExtJSJSONDataFormatter }
   TJSONObjectEvent = Procedure(Sender : TObject; AObject : TJSONObject) of Object;
+  TJSONExceptionObjectEvent = Procedure(Sender : TObject; E : Exception; AResponse : TJSONObject) of Object;
+
   TExtJSJSONDataFormatter = Class(TExtJSDataFormatter)
   private
     FAfterDataToJSON: TJSONObjectEvent;
     FAfterRowToJSON: TJSONObjectEvent;
     FBeforeDataToJSON: TJSONObjectEvent;
     FBeforeRowToJSON: TJSONObjectEvent;
+    FOnErrorResponse: TJSONExceptionObjectEvent;
     FOnMetaDataToJSON: TJSONObjectEvent;
     procedure SendSuccess(ResponseContent: TStream; AddIDValue : Boolean = False);
   protected
@@ -61,6 +64,8 @@ type
     Property AfterDataToJSON : TJSONObjectEvent Read FAfterDataToJSON Write FAfterDataToJSON;
     // Called just before response object will be streamed (response passed to handler).
     Property BeforeDataToJSON : TJSONObjectEvent Read FBeforeDataToJSON Write FBeforeDataToJSON;
+    // Called when an exception is caught and formatted.
+    Property OnErrorResponse : TJSONExceptionObjectEvent Read FOnErrorResponse Write FOnErrorResponse;
   end;
 
 implementation
@@ -343,6 +348,8 @@ begin
     If Length(L)>0 then
       ResponseContent.WriteBuffer(L[1],Length(L));
     Resp.Add(RowsProperty,TJSONArray.Create());
+    If Assigned(FOnErrorResponse) then
+      FOnErrorResponse(Self,E,Resp);
   finally
     Resp.Free;
   end;
diff --git a/packages/fcl-web/src/webdata/extjsxml.pp b/packages/fcl-web/src/webdata/extjsxml.pp
index 85517b5bd9..02e6951768 100644
--- a/packages/fcl-web/src/webdata/extjsxml.pp
+++ b/packages/fcl-web/src/webdata/extjsxml.pp
@@ -38,6 +38,8 @@ Type
 
   { TExtJSXMLDataFormatter }
   TXMLElementEvent = Procedure (Sender : TObject; AElement : TDOMElement) of object;
+  TXMLExceptionObjectEvent = Procedure(Sender : TObject; E : Exception; AResponse : TDOMElement) of Object;
+
   TExtJSXMLDataFormatter = Class(TExtJSDataFormatter)
   private
     FAfterDataToXML: TXMLElementEvent;
@@ -45,6 +47,7 @@ Type
     FBeforeDataToXML: TXMLElementEvent;
     FBeforeRowToXML: TXMLElementEvent;
     FDP: String;
+    FOnErrorResponse: TXmlExceptionObjectEvent;
     FReP: String;
     FRP: String;
     function IsDocumentStored: boolean;
@@ -74,6 +77,8 @@ Type
     Property BeforeDataToXML : TXMLElementEvent Read FBeforeDataToXML Write FBeforeDataToXML;
     // Called after all rows are appended to root element (passed to handler).
     Property AfterDataToXML : TXMLElementEvent Read FAfterDataToXML Write FAfterDataToXML;
+    // Called when an exception is caught and formatted.
+    Property OnErrorResponse : TXmlExceptionObjectEvent Read FOnErrorResponse Write FOnErrorResponse;
   end;
 
 implementation
@@ -148,6 +153,8 @@ begin
       C.AppendChild(XML.CreateTextNode(E.Message))
     else
       C.AppendChild(XML.CreateTextNode(SerrNoExceptionMessage));
+    If Assigned(FOnErrorResponse) then
+      FOnErrorResponse(Self,E,El);
     WriteXMLFile(XML,ResponseContent);
   Finally
     XML.Free;