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Last post Mar 17, 2012 04:06 PM by BrockAllen
Mar 17, 2012 12:28 PM|LINK
I am running my own web server (Windows 2008 R2 64-bit) with various ASP.NET 4.0 web applications and web sites running on it. Occasionally, I check out the Windows Event Log to see if an application or websites has generated a server error.
Every once in a while (about once in 2 weeks), I randomly see the following types of errors in he Event Log:
Event code: 4009
Event message: Viewstate verification failed. Reason: The viewstate supplied failed integrity check.
Event time: 16-3-2012 17:29:36
Event time (UTC): 16-3-2012 16:29:36
Event ID: db6e0d4d88384be4ac9f159de7bec1af
Event sequence: 10
Event occurrence: 1
Event detail code: 50203
Other than the fact that I have absolutely no idea where this error is coming from, it also appears to be really random. I've seen this error appear on pages with simple contact forms (name, e-mail address and message) to complicated forms with dozens of
dynamic fields ("Get a quote!"-forms and the like). What exactly does it mean? Does it mean that someone is trying to do something malicious (Cross-Site Scripting / XSS?) and this creating an 'invalid viewstate'? How can a Viewstate become 'invalid anyway?
Mar 17, 2012 12:31 PM|LINK
This may be config issue related to machinekey....
More details here...
Mar 17, 2012 04:06 PM|LINK
I've seen this happen when sometimes users post back the page before the page has had a chance to load fully into the browser, and thus not all the form fields get posted back to the server. given the missing input elements, this could cause the viewstate
validation to fail.