In support desk there have been several reports of MediaWiki upgrades failing on MediaWiki 1.33 when running the migrateActors script. The error happens because there's apparently a duplicate actor_name with empty value:
A database query error has occurred. Did you forget to run your application's database schema updater after upgrading? Query: INSERT INTO `actor` (actor_name) VALUES ('') Function: MigrateActors::addActorsForRows Error: 1062 Duplicate entry '' for key 'actor_name'
Reports in Support Desk: