report server hangs and fails - ASP.NET 'Viewstate verificaion failed'

jostick used Ask the Experts™
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!
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The browser version used will have no bearing whatsoever on the errors you find on th server. The viewstate immediately made me think about load balancing or some kind of proxying that might be taking place between the web server & a client or another client that needs to persist session information.
Can you check your IIS settings under ASP.NET configuration on both the application specific and the Global Configuration as seen on the attachment?


How hard would it be to update your IIS server to the latest sp?
Here we go:;en-us;555353
1. Adjust the settings on the application pools so that recycling is less likely to occur at peak periods.
2. Use a specific key in the machine.config to prevent automatic key generation on each process start
3. Only post to the same ASPX page
4. Turn off firewall and antivirus software
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It can also be a pool limit.
You can check you server's machine.config to make sure it follows the Formula for Reducing Contention. (See attached)
jostickIT Manager


myrotarycar:ond to all sugestions:

myrotarycar: The inly ASP seetg tyhat I could find were inthe control panel and were for ASP 1 and looked nothing like your example. We have Windows server 2003 (SP2), SQL 2005. >NET  3.5 is actually installed on it.
I don't think there could be a problem with recycling at peakperiods. The problem always occurs, even immediatly after a server restart and nobody else using report server. Possibly AV problem, but do I need to be looking at server or client for this?

13598: We have IIS6. Can this be upgraded under WIndows 2003? Either way, it would be could to find the casue of the problem first. I looked at machine.config, and coul; dnot work ourt where to make the new settings. However,  I haveto say that it wa working fine for ages then began to fail, so I suspect that the machine.config may be OK. The server itself has minimal load.

Thanks for suggestions. Sorry, if I appear to repond negativly to them , just trying to be objectiuve.

I understand but please you also need to understand how hard it is for us without having the machine or the whole story in front of us to make suggestions.
I suggested to upgrade your IIS because you said it was working fine until you upgraded to IE8 and I figured if it wasn't hard for you to upgrade it could take care of the issue.
Did you try installing .net 3.5 on the server? Net 2.0 is rather old and  IE8 may need 3.5 to run correctly? It keeps the previous version you would have both 2.0 and 3.5 on the server so it would probably not be an issue.
Also make sure you Have IE8 running with compatibility mode.
jostick, no apologies necessary. We've all been there -and have had probems nagging us.
Take a look at suggestion #2 from the TechNet article: hardcode a static key on the application machine.config; here is how
Your client's framework version & browser will have no bearing at all on your server's viewstate. Viewstate, if you read the first article I posted, prevents any cached content on the server from being modifed in-cache. This effectively prevents malicious changes from being done outside of the framework interpreter. Hope it helps! And good luck!
jostickIT Manager


OK. Problem solved!

Its caused by AVG 9, specifically the linkscanner component. This AVG forum thread is related to it:

How frustrating!!!!!

Thanks for taking the time to make suggestions. Really very much appreciated. I've accepted one of your posts as the solution, as it prompted me to look more closly at the AV. Cheers!
jostickIT Manager


The AV suggestion led me to look at the AV a bit closer. Problem was in there.

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