Upgrading
From MoodleDocs
Moodle is designed to upgrade cleanly from any earlier version to any later version.
When upgrading a Moodle installation you should follow these steps:
Backup important data
Although it is not strictly necessary, it is always a good idea to make a backup of any production system before a major upgrade, just in case you need to revert back to the older version for some reason. In fact, it's a good idea to automate your server to backup your Moodle installation daily, so that you can skip this step.
There are three areas that need backing up: