Error while using Update Panel

I am getting error as

Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed.' when calling method: [nsIDOMEventListener::handleEvent]

I am using Update Panel for Gridview and I want to export that grid to Excel or PDF.

So the code contains Response.Write()

If i remove update panel then it works fine but i want update panel too for UpdateProgress.

what can be done?