Reports have begun hanging then timing out on an installation that has been OK for a long time. Its associated with an error in the event log:
Event Source: ASP.NET 2.0.50727.0
Event Category: Web Event
Event ID: 1316
Event code: 4009
Event message: Viewstate verification failed. Reason: The viewstate supplied failed integrity check.
This happens when I try to run the report on any PC or even on the server itself. I did some research and it looked like it might be an IE 8 problem - this woul d makes sense as we have recently begun using IE8. However, it happens on Firefox 3.5 also.
The only offical info suggested that this particular viewstate error is to do with server farms, but this doesn't apply to us.
One question, maybe related, is why the IIS server (Windows 2003) is using .NET 2, when the client PCs have all upgraded to 3.5. Is this relevant?
Suggestions appreciated. Thanks!