I had the same exact thing happen when updating to 1.28.0599 on my Asustor.
This version seems to be corrupting the database.
I got stuck on 5897 and it wouldn’t update either. I also couldn’t open Plex but after an uninstall and reinstall it came back so I just left it on 5897. Maybe I got away without corrupting my database but it sounds like you might not have gotten so lucky.
You’re probably going to have to repair the database but you might want to wait for an employee to verify that.
If you’re feeling brave you can follow the instructions ChuckPa gave in another thread.
On another note, i’m curious now
Backing up the database from an older version now, does this mean a corrupted database will happen again in the near future from another update?