Good that your database is not corrupt.
I run Plex on Ubuntu. I’ve never run it on truenas or in docker, so can’t help with that part.
I also have media on a Synology NAS, and getting permissions working took a bit.
Squashing all users to admin should be OK. Also set security to sys if you’re not using kerberos. It is right under the setting where you squash to admin in Syno NFS permissions.
You may want to try setting permissions to 755 after mounting the NFS shares. It is recommended in Linux Tips - Mounting NFS network shares for Plex use. I’m not sure how you do that when running Plex in a docker container.
FWIW, I took a slightly different route. I set the Synology to NFSv3 instead of NFSv4, then matched the user id & group between Ubuntu and Synology for plex:plex. I then make sure plex:plex on Synology has at least read-only permissions to the media files.
I’ve never seen that message before. I searched the forum and found one hit. That system had run out of space on the drive holding the database. However, there was also a SQLITE error message saying “out of space.”
