After upgrading Symantec Messaging Gateway 9.5.2 from 9.5.1 the GUI shows the error: 'The Control Center is unable to connect to the database. Either the database is not running or the password for brightmailuser is incorrect'
1. Login in to an SSH session and run 'service mysql start' and problem should be gone.
2. Perform a check up after step 1. Reboot the full SMG and check the status of the services by running the commands service service-name status: if they are all up and running problem should be gone. If some service still down go to step 3.
3. If some services are down and mostly mysql follow the steps:
3.1. Start up all services by commands in SSH session.