Looks like the mysql password was out of sync when the installer was started.
I'm happy you had a backup. You should restore, then reset all the the passwords (LDAP, MYSQL, and Logger) before running the upgrade.
The instructions for how to do this can be found here:
http://wiki.zimbra.com/index.php?tit...ySQL_Passwords
Good luck, and let us know if you need help
john