Here how to upgrade from old version to version 2.3.0:
1. Please back up your config.php. Just in case, it is recommended to back up your current database.
2. Replace all files within with the new ones. (Tips: you can create new folder filled with new files from latest version. Then you just need to replace config.php with your old one)
3. Go to folder staff and access upgrade23.php (e.g: http://yourdomain.com/support/staff/upgrade23.php)
This is needed because new script will not granted any login before you upgrade the database with upgrade23.php
4. Your database will be updated. Then you need to rename or removed upgrade23.php because this file is accessible by outside.
5. Please do some changes: Ticket Categories, Front HTML, Email Templates, General Setting.
Old email templates won't be replaced, just new templates are added and you just need to edit those ones.
6. You need to modify your front template to suit with your website. Old front template will not suit again with this version. This is mandatory step.
7. Beside config.php there is now config_ext.php. It stores configuration values for helpdesk: date format, file attachment allowed, etc.