Just guessing here, but the upgrade might have replaced your databases and now cannot find the WordPress database name and/or table_prefix specified in wp-config.php. If that is the case, your site (SQL database) is likely gone unless you had a backup.
Thanks for the reponse.
In phpmyadmin I can still see the databases and table content. So that’s all intact.
All databases use the wp_ prefix as specified in wp-config.
I know the db user/pw is setup ok because all sites use the same db user for test purposes and my non-wordpress sites are working fine with this user.
I’ve got backups but I’d like to understand why its all gone wrong.
