During the process of migrating the first of these applications into SharePoint, I discovered that the ScriptManager tag was causing an “An unknown error has occurred” in SharePoint. The only odd thing was, that I have PageMethods enabled on the script manager tag. In this page I was using an Auto Complete Extender from the AJAX Control Toolkit and had configured it to point to a pagemethod.
There was nothing in the SharePoint logs, nor in the Event log so I disabled SharePoint error handling and found the following exception was being thrown.
Server Error in ‘/’ Application.
Directory ‘C:\Inetpub\wwwroot\wss\VirtualDirectories\80\_catalogs\masterpage’ does not exist. Failed to start monitoring file changes.
Update: Having applied the hotfix, Ifound that the problem remained, my only option to fix my original problem at this point was to re-implement my pagemethod as a webservice. I was reluctant to do this at the outset because it seemed a waste to create a webservice just for a single (page) method. Nevertheless, I duly did so, reconfigured my Auto Complete Extender to point to the webservice and my problem was solved.