Disable viewstate on IIS 7.5

We encountered a problem with viewstate encryption on Windows 2008 R2 and Windows 7. The page in question does a post with javascript to provide default values for parameters for another page. Only on IIS 7.5 this generates the error below.

[HttpException (0x80004005): Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.]

This is a feature of IIS to avoid tampering with the viewstate and cookies. The viewstate of Page X is posted to Page Y and fails the Message Authentication Code (MAC)

We don’t need the viewstate so we disable it. But even with EnableViewstate = “false” the server generated the __VIEWSTATE hidden field.

No more mister nice guy! :mrgreen: We added the javascript below in the post code to remove the viewstate. No more viewstate, no more exceptions.


var vs = document.getElementById("__VIEWSTATE"); 

Code from jberda answer on ASP.NET forum.


Disabling viewstate is not recommended. (Details) Use it wisely.

About erictummers

Working in a DevOps team is the best thing that happened to me. I like challenges and sharing the solutions with others. On my blog I’ll mostly post about my work, but expect an occasional home project, productivity tip and tooling review.
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