Sys.WebForms.PageRequestManagerServerErrorException 12031

Question

I\'m occasionaly getting the following popup from an AJAX.NET application

Sys.WebForms.PageRequestManagerServerErrorException: An Unknown error occurred while proc         


        

Answer 1

I've got this error in UpdatePanel with autopostback Dropdown after big delay (>20 min) between change dropdown selection.

Try increase session timeout in web.cofig. For example:

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