Bumped into this issue where both APM websites (Applications Diagnostics and Application Advisor) didn’t work as expected. Instead both websites threw this error:
So it was time for an investigation of things on the side of the related websites, or better the related Application Pools in IIS Manager (OperationsManagerAppMonitoring and OperationsManagerMonitoringView):
Hmm. That’s not good. Identities like these don’t have access to the related SQL database.
Let’s change the identity to an account which has SQL permissions on that DB. In this case I have chosen an AD account which has SA permisions on the related SQL instance. No big deal here since it’s an OpsMgr SQL instance only .
So whenever you bump into a similar issue check the identities used by the two Application Pools used for the APM websites (OperationsManagerAppMonitoring and OperationsManagerMonitoringView). Changes are they use the default ones which don’t have access to the SQL database.