Did your disk run out of space at some point (in the LXC). Go to /etc/jellyfin in the LXC and if migrations.xml is zero bytes, delete the file and restart Jellyfin.
Jellyfin 10.10.3 (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)