Sys.WebForms.PageRequestManagerTimeoutException: The server request timed out.

To increase the timeout you can adjust the ScriptManager.AsyncPostBackTimeout value.

http://stackoverflow.com/questions/158975/asp-net-updatepanel-time-out

http://stackoverflow.com/questions/2210554/potential-problems-in-setting-asyncpostbacktimeout-to-large-value-300s

http://msdn.microsoft.com/en-us/library/system.web.ui.scriptmanager.asyncpostbacktimeout.aspx