Telerik RadAjax controls won't work on browsers that do not support XmlHttp requests. You may want to disable AJAX when such a browser opens your site. This could be easily achieved by setting the EnableAJAX property of used Telerik RadAjax control to false both on client- and server-side.

The .NET2 framework provides SupportsXmlHttp property and it should be used to check if the browser supports XmlHttpRequest:

• C#
• VB

CopyC#

RadAjaxManager1.EnableAJAX = Page.Request.Browser.SupportsXmlHttp;

CopyVB

RadAjaxManager1.EnableAJAX = Page.Request.Browser.SupportsXmlHttp

When this check is made in Page_Load event handler it will make your page work as in standard postback scenario for those browsers.

Caution
Some browsers do support xmlhttp requests and still return false for SupportsXmlHttp. In such cases you should define Browser definition files - more info is available in the links below.