If you have got this error: “Sys.WebForms.PageRequestManagerTimeoutException The server request timed out” from the Ajax Extension framework. It is because you have not mentioned the timeout period for the script manager on your page. The default timeout period of script manager is 90 seconds, so if your process takes more than 90 seconds you will be presented this error.
Add a property AsyncPostBackTimeOut to your script manager as following:
<asp:ScriptManager ID=”ScriptManagerAjax” runat=”server” AsyncPostBackTimeout=”720″>
The timeout period is in seconds that is 12 minutes. You can specify it according to your need.
Hope this helps! Happy Programming!