Migrating from Debian to Ubuntu

[Broom5229]

Hello all, I'm having an issue that I can't seem to find any answers for and I've been searching for a few hours. So I'm moving from an old, "gonna die any day" Debian machine to a much higher spec'd (by comparison) Ubuntu device. I mainly used this Reddit post since there doesn't seem to be any documentation on moving from Linux to Linux: https://www.reddit.com/r/jellyfin/commen...ux_server/. In keeping with that post, I installed Ubuntu on the new device, installed Jellyfin, moved my /etc/jellyfin and /var/lib/jellyfin directories over, and changed the permissions using chmod 777 (I know that's not great, moving on). I was able to get a point where my new server does indeed see that there's an existing database, but it keeps saying I have the wrong username/password and it won't let me reset the password even when I'm on the same network (no VPN, same subnet, etc, I can't possibly be any more on the same network). Am I doing something wrong? Did I miss a step? Or is this migration simply not possible? My main concern is keeping watching history/progress but it would also be nice if I can keep users and passwords so my friends/family using the server can just log in as if nothing happened.

Thanks in advance. Happy to share any logs or additional info, but I'm kind of a newb when it comes to server administration so you may need to tell me where they are.