The login you specified when connecting to server instance '{0}' has limited permissions for monitoring database mirroring. ...

The login you specified when connecting to server instance '{0}' has limited permissions for monitoring database mirroring. It is a member of the dbm_monitor fixed database role in msdb, but not a member of the sysadmin fixed server role. Because the dbm_monitor role has limited permissions, you cannot set warning thresholds through this connection.

To see updated status of your mirroring sessions, ensure that the 'Database Mirroring Monitor Job' is configured and that SQL Server Agent service is running. Refreshing the Database Mirroring Monitor displays the most recent row from the status table; it will not update the status table.