In your page http://www.telerik.com/help/aspnet-ajax/autocompletebox-onclientrequestfailed.html you only have one message to show to the user, why not return de http status code? In this moment the workaround suggested by your team is: <script> Telerik.Web.UI.WebServiceLoader.prototype._onWebServiceError = function (error, context) { var errorEventArgs = new Telerik.Web.UI.WebServiceLoaderErrorEventArgs(error.get_statusCode().toString(), context); this._raiseEvent("loadingError", errorEventArgs); } function OnClientRequestFailed(sender, args) { console.log(args.get_errorMessage()); } </script>