title: Validation of viewstate MAC failed -View State Error
body: <p>In my website, when a web page is idle for more than 5 minutes, then that page is not working until I refresh. The following error occurs:</p>
  
  <blockquote>
    <p>Error:
    Sys.WebForms.PageRequestManagerServerErrorException:
    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>I'm already using <code>EnableEventValidation="false"  ViewStateEncryptionMode="Never" ValidateRequest="false"</code></p>
  
  <p>But, nothing is working for me.</p>