If you got the below error message in your website,
"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."
Please try to add below code in your web.config file to fix it.
<pages enableViewStateMac="false" />
For more details, you can see this link.