Last week I had a problem when I tried to export an image from the AGS 9.2 to a pdf file. I got this error: "Sys.WebForms.PageRequestManagerTimeoutException The server request timed out" from the Ajax Extension framework. Its occurred because the export operation was relatively long (something like 2 minutes) and the Ajax Extension Callback framework had a timeout.
How to solve this problem?
To solve this problem we can increase the timeout. You can change the timeout time by adding a new property to the script manager control. This property is called AsyncPostBackTimeOut and it can help us to define the number of seconds before the request will throw a request timeout exception*.
For example if you want that the timeout will take maximum 10 minutes your code should be look like this:
<asp:ScriptManager ID="ScriptManager1" runat="server"
* The default value of the AsyncPostBackTimeOut property is 90 seconds.