> Fortunately I had the old database backed up

You say this as if it wasn’t Immich itself that backed up the database automatically next to your image files.

I think they’re one of the best self-hosted services when it comes to backup/restore — enabling it by default — and when it comes to migrations — no breaking changes in minor versions after 1.0.

Did you report this issue so I could try and reproduce it?

I had an issue where my thumbnails were borked somehow, so I deleted them all. However, I didn't delete the database entries, so they never got regenerated.

I ended up doing that manually, but it's great to see that is now a first class citizen in 3.0.0. I love Immich.