Spent some time struggling to upgrade my old Postfix Admin install from 2.1.0 to 126.96.36.199, kept running up against the following error:
Invalid query: Can't create table './postfix/vacation_notification.frm' (errno: 150)
Seems like others have had this, but I didn't find a solution posted. Some time Googling and investigating MySQL docs finally had me stumbling across the answer. The MySQL user 'postfixadmin' wasn't originally granted sufficient privileges to the database, and a prior ALTER step hadn't executed, and more importantly, hadn't been flagged as an error. Granting this user the ability to Alter, Create, Drop, and all other structure related commands then running the setup.php again resolved the issue.
Hope this helps someone out there.