Installed Enterprise ArcGIS 10.9.1. Had validated the datastore with ArcGIS Server manager. Month later, couldn't publish to the datastore. Datastore unable to validate. Also checked Server Administrator - 'Invalid Token'. Tried unregistering and re-registering the Datastore. DescribeDatastore - the "Portal for ArcGIS URL" is empty. Also tried a test to run 'Updatelicense' - unable to generate a token.
Tried uninstalling and reinstalling the Datastore (was going to restore from backup). Same result. Checked Federation it validates okay. Thanks