I'd suggest to try upgrading to 1.6 ST (ST = Stable) first.Once you have successfully done that upgrade to 1.6 ST, backup your database and the osTicket files on your webserver.After the backup, try to upgrade to 1.7.x or 1.8.x or 1.9.x. When the upgrade e.g. to 1.7.x worked, again, make a backup of your database and the osTicket files on your webserver. When a upgrade then fails, revert to the backup you've taken before your last upgrade attempt.Do this procedure (backup, upgrade, backup, upgrade, and so on) until you're at 1.9.12 or until an error appears. If the latter happens, let us know the error details.