How to Upgrade
Note that you can directly upgrade from one version to another. For example, to upgrade from version 3.1 to version 3.5, it is not necessary to first upgrade to version 3.2, then to version 3.3, and so on.
Upgrading can take a while depending on the size of projects portfolio. To monitor the process, check the logs and the console.
Upgrade is completed when an analysis has been run on project. Only at that point will you get new functionality working for sure.
Release Upgrade Notes
Usually Sonar releases come with some specific recommendations for upgrading from the previous version. You have to read the upgrade notes for all versions between your current version and the target version.