Question

ValidateEvents is a great ASP.net function, but the Yellow Screen of Death is not so nice. I found a way how to handle the HttpRequestValidationException gracefully here, but that does not work with ASP.net AJAX properly.

Basically, I got an UpdatePanel with a TextBox and a Button, and when the user types in HTML into the Textbox, a JavaScript Popup with a Error message saying not to modify the Response pops up.

So I wonder what is the best way to handle HttpRequestValidationException gracefully? For ‘normal’ requests I would like to just display an error message, but when it’s an AJAX Request i’d like to throw the request away and return something to indicate an error, so that my frontend page can react on it?

Answer 1

Found it and blogged about it. Basically, the EndRequestHandler and the args.set_errorHandled are our friends here.

<script type='text/javascript' language='javascript'> var prm = Sys.WebForms.PageRequestManager.getInstance(); prm.add_endRequest(EndRequestHandler);  function EndRequestHandler(sender, args) {     if (args.get_error() != undefined)     {         var errorMessage;         if (args.get_response().get_statusCode() == '200')         {             errorMessage = args.get_error().message;         }         else         {             // Error occurred somewhere other than the server page.             errorMessage = 'An unspecified error occurred. ';         }         args.set_errorHandled(true);         $get('<%= this.newsletterLabel.ClientID %>').innerHTML = errorMessage;     } } </script>