I assume you mean upgrade from 1.15.4 to 1.17.x and not 1.7. The second number is said as a number ("seventeen") and not as digits ("One-seven") and so 1.17.x is higher than 1.6.x. I also found it confusing when I first started. We recently upgraded from 1.14 to 1.17 without any hassles. Make sure you take a full backup of your site files and database and make sure you install the updated plugins as well.
- Disable email fetching and set site to offline
- Backup site folder and database (we just backed up the whole VM in hyper-V, not sure what you are using)
- Apply any OS level upgrades and updates
- Upgrade and update PHP and MySQL (and your web host thingy, whatever the Windows equivilent of Apache is) if needed. Check Docs for the correct versions, latest PHP version is unsupported (I don't know it off the top of my head)
- Upgrade osTicket by extracting and copying in all the files -> Documentation
- Upgrade plugins by copying in new .phar files into Plugins folder
- Add any language packs you had back in i18n folder
- Copy back in your ost_config file ([root]/Include/ost_config.php)
- Sign into osTicket as an Agent and follow prompts for the upgrade process
Here's a brief overview from another thread. But definitely backup and test your backup to make sure you can get back to square 1 if needed.
