Auto-Update definitely missed this issue for sure. Same thing happened to me.
The easiest way to regain access to your adminpanel is to FTP into your server and overwrite the wordpress files with your backup files.
If you didn’t save your backups then you’ll either need to overwrite them with an older version, or upgrade your mysql database to version 5. I’ll do this eventually, just haven’t looked into what’s involved yet.
Backup all your files before doing anything just to be safe. Good Luck!
