Going by what the error said, we re-installed Silverlight on both the server and the client machine. No luck. After doing a Google search we learned that the error was caused by the Web Page Security Validation Web Application setting being set to Off.
To resolve the issue, follow the steps below:
- Login to Central Admin
- Select Application Management - Manage Web Applications.
- Select the Web Application you were having the problem with, then select General Settings from the ribbon.
That's it. Never has an error message given so little information to resolve the real problem!
Let us know if you have a similar issue.