Question

I have an ASP.NET application all things are working fine but after some minutes when I click on a button it gives me this error :

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. Description: An
unhandled exception occurred during
the execution of the current web
request. Please review the stack trace
for more information about the error
and where it originated in the code.

Exception Details:
System.Web.HttpException: 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.

How I can resolve this ?

Answer 1

This blog post covers this in quite a bit of detail:
http://www.eukhost.com/forums/f15/fix-validation-viewstate-mac-failed-6085/

In the past i’ve used this method:

  <system.web>
  <pages enableViewStateMac="false" />
  </system.web>