Open a terminal window for unRAID, navigate to where you are mounting /config. In that folder will be another "config" directory, delete or rename system.xml and migrations.xml and restart the container.
Jellyfin 10.10.0 (Docker)
Ubuntu 24.04 LTS
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
3x WD Red Pro 6TB CMR in RAIDZ1 (JF Library)