I get this error when I try to do an async postback.
The page used to work OK. A branch of it still works OK! I noticed that it stopped working for the first time today. Today I installed the Visual Studio 2008 and .net 3.5 sp1 combination on my PC (intel processor, Win XP pro, sp3).
The error Message is:
Microsoft JScript runtime error: Sys.WebForms.PageRequestManagerServerErrorException: Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.
I disabled ViewState for the page and every control on the page.
In debug mode, when the error happens, I get dumped into javascript inside this code
ScriptResource.axd?d=4CaE etc etc etc.... some very long number
at this point, precisely on line 4723 below.
4694&nb ...
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