If both of the following conditions are true, you will need to take the extra steps outlined in Transferring data from MySQL to PostgreSQL when upgrading the supervisor:
We have seen cases with customers upgrading from Qube 6 to Qube 7 where the supervisor is attempting to connect to the PostgreSQL server on the default port for MySQL. This is due to the database_port being defined in the qb.conf file, but still set to the value for a MySQL server.
Qube! versioning is indicated by major, minor, and point releases in the format major.minor.point (e.g. 5.5.0).