Moving libraries to a different disk

[jellyfin]

I now also tried https://github.com/jellyfin/jellyfin/discussions/6924 with the given SQlite commands, but I still get all movies doubled, and the new entries are clearly from a fresh scan, as they have no changes done by me to the metadata and often point to a wrong movie, title or image.

I am short before giving up.

It is like the developers tried really hard to make migrations impossible!
But they implemented an easy way to change the location for the Jellyfin configuration itself ..

Unbelievable.