SOLVED: I restarted my server from web (button), but failed to restart.

[TheDreadPirate]

Since you are running Jellyfin directly on Ubuntu, /opt/jellyfin is not used. Just delete that directory and the script you created. And you should not be starting jellyfin simply by typing "jellyfin", which is what appears to be happening.

You need to be using systemctl to manage jellyfin.

Code:

sudo systemctl restart jellyfin

Stop, start, and status are also valid commands.

As for the "restart" button in the web, I also noticed this issue and there appears to be an open issue already.

https://github.com/jellyfin/jellyfin/issues/12161