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. Resolved

[Resolved]

 Solution:


<system.web>
 <pages viewStateEncryptionMode="Never" enableEventValidation="false" validateRequest="false">
    </pages>
     <machineKey  decryptionKey="2CC8E5C3B1812451A707FBAAAEAC9052E05AE1B858993660" validation="HMACSHA256" decryption="AES" validationKey="CB8860CE588A62A2CF9B0B2F48D2C8C31A6A40F0517268CEBCA431A3177B08FC53D818B82DEDCF015A71A0C4B817EA8FDCA2B3BDD091D89F2EDDFB3C06C0CB32" />
    <customErrors mode="Off">
      <error statusCode="404" redirect="/404error.aspx" />
    </customErrors>
</system.web>

  Error:
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.

  Error Snap shot