How to use the ASPxWebControl.CallbackError event to handle application-level errors occurred inside ASPxWebControls during callback processing

This example illustrates how to catch and handle:
- Exceptions that occur inside DevExpress ASP.NET controls during a callback using the ASPxWebControl.CallbackError event;
- The remaining unhandled exceptions using the Application_Error event in the Global.asax file.
It also shows how to write required information to the same log/storage (for further diagnostics, etc).

Global.asax:

[C#]
voidApplication_Start(objectsender,EventArgse){// Assign Application_Error as a callback error handlerASPxWebControl.CallbackError+=newEventHandler(Application_Error);}

[VB.NET]
Sub Application_Start(ByVal sender AsObject, ByVal e As EventArgs)
    ' Assign Application_Error as a callback error handlerAddHandler ASPxWebControl.CallbackError, AddressOf Application_Error
EndSub

[C#]
voidApplication_Error(objectsender,EventArgse){// Use HttpContext.Current to get a Web request processing helperExceptionexception=HttpContext.Current.Server.GetLastError();if(exceptionisHttpUnhandledException)exception=exception.InnerException;// Log an exceptionAddToLog(exception.Message,exception.StackTrace);}

[VB.NET]
Sub Application_Error(ByVal sender AsObject, ByVal e As EventArgs)
    ' Use HttpContext.Current to get a Web request processing helperDim exception As Exception = HttpContext.Current.Server.GetLastError()
    If TypeOf exception Is HttpUnhandledException Then
        exception = exception.InnerException
    EndIf' Log an exception
    AddToLog(exception.Message, exception.StackTrace)
EndSub

By default, an unhandled exception occurs while a callback is displayed using the "alert" message.
In order to execute redirect to a custom error page, specify the callbackErrorRedirectUrl configuration option:

Web.config:

[XML]
<configuration><devExpress><errorscallbackErrorRedirectUrl="~/ErrorPage.aspx"/></devExpress></configuration>

MVC Version:
How to use the ASPxWebControl.CallbackError event to handle application-level errors occurred inside ASPxWebControls during callback processing