I host my own Lemmy instance and have a user account on it that I use everywhere (I don't host local communities, I just use it as a home for my Lemmy user account). I needed to re-home my Lemmy server, and though it's a docker installation, copying the /var/lib/docker/volumes/lemmy_* directories to the new installation didn't work. So I created a new Lemmy server.
How can I move my old account to the new server, so I can keep all my subscriptions and post/comment history?
I don't recommend re-installing an instance on the same domain. This caused me errors before I had to replace my domain. Like I couldn't subscribe to same communities with my old username. If you have the old data, you should find a way to extract it.
I've had that problem too (messing around with test instances) - for anyone else wondering why: it's because the RSA keypair for me@mydomain has changed, and remote instances fail to validate message headers signed with the new private key, because they're still using their copy of an old public key.
My new server uses a new domain. I do still have the old data (in fact, the old server is still up - that's where I'm posting this from).
I installed both Lemmy servers via Docker. It would be nice if I could rsync my account data (including post/comment history) from the old server to the new server, but I'm now wondering if my changing domains would make the old account not work at all in the new server.
I guess there is no way to move your post/comment history to a new domain. It's like if you change your domain then you can't use old DB and if you don't change it then you can't re-install with fresh DB :)