ASP.NET Web Forms - How to handle application-level errors occurred during callbacks

Use the static ASPxWebControl.CallbackError event to handle callback exceptions thrown by DevExpress web controls server side. Delegate callback exception handling to the Application_Error event handler.

void Application_Start(object sender, EventArgs e) {
    // Assign Application_Error as a callback error handler
    ASPxWebControl.CallbackError += new EventHandler(Application_Error);
}

Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
	' Assign Application_Error as a callback error handler
	AddHandler ASPxWebControl.CallbackError, AddressOf Application_Error
End Sub

The Application_Error event handler catches all unhandled ASP.NET errors while processing a request. You can use the GetLastError method to get and log the details of the last exception.

void Application_Error(object sender, EventArgs e) {
    // Use HttpContext.Current to get a Web request processing helper
    Exception exception = HttpContext.Current.Server.GetLastError();
    if (exception is HttpUnhandledException)
        exception = exception.InnerException;
    // Log an exception
    AddToLog(exception.Message, exception.StackTrace);
}

Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)
	' Use HttpContext.Current to get a Web request processing helper
	Dim exception As Exception = HttpContext.Current.Server.GetLastError()
	If TypeOf exception Is HttpUnhandledException Then
		exception = exception.InnerException
	End If
	' Log an exception
	AddToLog(exception.Message, exception.StackTrace)
End Sub

When a callback exception occurs, you can redirect the application to another web resource. Use the callbackErrorRedirectUrl configuration option to specify the redirection location.

<configuration>
    <devExpress>
        <errors callbackErrorRedirectUrl="~/ErrorPage.aspx"/>
    </devExpress>
</configuration>

Note

There are controls (for instance, ASPxUploadControl) that utilize the capabilities of the DevExpress.Web.ASPxUploadProgressHttpHandler handler to perform actions on a callback. System-level exceptions (request timeout, session timeout, etc.) that occur while executing the ASPxUploadProgressHttpHandler handler cannot be handled using the ASPxWebControl.CallbackError event. Use the default Application_Error event handler for this purpose.

Files to Review

• Global.asax (VB: Global.asax)
• Web.config (VB: Web.config)

Documentation

• Callbacks

More Examples

• ASP.NET MVC - How to handle application-level errors that occurred during callbacks

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