Knowledgebase: PHP, ASP & CGI/Perl
Validation of viewstate MAC failed
Posted by David Miles-Watson on 05 February 2014 02:50 PM

If you receive the following error:

The state information is invalid for this page and might be corrupted.

Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.


Using a text editor, add the following setting to the Web.config file:

<machineKey validationKey="14829C6F4F1B51ED0F3B18C9B7746CA1A6D391B400B8CE693C1D759D526C97509DB003CDE4AC4F662092A4568824A941CBD7249A222C0D39C9292496AC60780F" decryptionKey="DE1C668166AAAF583E868F2B1EE09EBFB7F5CF0A831D293C" validation="SHA1" />

Alternatively, you could generate a new 'machineKey' using free online tools.

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