Fixing Validation of viewstate MAC failed issue
Some customers reported Validation of viewstate MAC failed issue after upgrading their on-premise environments to KanBo 2.2 version.
Server Error in '/' Application.
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.
Following solution is not recommended for production environments - you should install ASP.NET KB 2905247 update instead.
You can solve this issue by adding <pages> element in the web.config, like this:
<configuration> <system.web> <pages enableViewStateMac="false" /> </system.web> </configuration>