I noticed that few weeks back Jellyfin service was dead and would not restart. There were no logs, just that systemd service was not found if I remember correctly. When trying to access it through the browser I got a 502/nginx error.
So I uninstalled it and tried to restore it though the latest backup I had, but without success.
if you get a directory list you can reinstall Jellyfin from an earlier backup or from scratch. If you get a “not such file or directory” error then you need reinstall your yunohost server due something broke systemd and your server will stop working when you reboot it