Synology Content Manager - Nach Update gehen Benutzer und Einstellungen verloren

[TheDreadPirate]

If I'm reading your screenshots correctly, you did not provide a host volume for /config and /cache. Meaning that they only existed in the TEMPORARY file system the container created. When you upgrade a container it deletes the old and and creates a new one. Including the temporary file system it creates.

Before you get too far into recreating your Jellyfin, reconfigure the container and provide a path on the host for the container to write /config and /cache to. You will need to restart again, but this should not happen again in the future once you do this.