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I am getting validation of view state MAC failing but only very very occasionally.

I am not in a web farm and can't recreate this.

Are there any known factors that can make view state MAC validation fail?

AJM
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  • see also : http://stackoverflow.com/questions/1821243/cryptographicexception-padding-is-invalid-and-cannot-be-removed-and-validation/2551810#2551810 – Aristos Feb 26 '13 at 16:28

1 Answers1

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Microsoft blogger Tess Ferrandez has a pretty good post on this:

Viewstate and viewstate validation use a couple of hidden form fields like __VIEWSTATE and __EVENTVALIDATION. If the page renders so slowly that the __EVENTVALIDATION field has not rendered by the time someone clicks the button or control that causes the postback, ASP.NET will also believe that the viewstate is invalid and report this.

Check whether your viewstate is very large in the problematic page(s). You may want to turn off EnableViewState property on controls that don't need it, especially large databound controls that don't need to remember their state between postbacks.

mellamokb
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