Some versions of django CMS present more complex upgrade paths than others, and some require you to take action. It is strongly recommended to read the release notes carefully when upgrading.
It goes without saying that you should backup your database before embarking on any process that makes changes to your database.
3.7 3.6 3.5.3 3.5.2 3.5.1 3.5 3.4.4 3.4.3 3.4.2 3.4.1 3.4 3.3 3.2.5 3.2.4 3.2.3 3.2.2 3.2.1 3.2 3.1.5 3.1.4 3.1.3 3.1.2 3.1.1 3.1 3.0.16 3.0.15 3.0.14 3.0.13 3.0.12 3.0.11 3.0.10 3.0.9 3.0.8 3.0.7 3.0.6 3.0.3 3.0 2.4 2.3.4 2.3.3 2.3.2 2.3 2.2 2.1