Validation of viewstate MAC failed.

Question

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.

How to over come this................

Rahul Saxena · Answer

I found many for this someone told me to set config pages> tag inside system.web > pages theme =  Default  validateRequest =  false  enableEventValidation =  false  viewStateEncryptionMode =  Never  enableViewStateMac =  false  > Finaly I got that the web farm number in Application pool is greater then 1 it shouldn't.