title: how to solve viewstate MAC failed in asp.net
body: <p>I'm facing this problem on server and localhost both place</p>
  
  <blockquote>
    <p>Error:</p>
    
    <p>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.</p>
  </blockquote>
  
  <p><img src="https://i.stack.imgur.com/jbM8Z.png" alt="enter image description here"></p>