When a RadButton with a PostBackUrl property set is located inside an UpdatePanel, it does not redirect to the PostBackUrl on click and a JavaScript error message is thrown. The workaround is to use: - Either a RadButton (ButtonType="LinkButton") and set its NavigateUrl to the desired page that is to be redirected -OR a RadButton (ButtonType="StandardButton") and use its OnClientClicking event handler to cancel the postback and redirect to the desired page through window.location.href. For example: <script type="text/javascript"> function OnClientClicking(sender, args) { window.location.href = "http://www.bing.com"; args.set_cancel(true); } </script>