If you are currently on a version before the latest one, make sure you follow the upgrade instructions for all previous releases up to the version prior to latest before proceeding to the latest version.
Note: 2.0.0-2.0.6 users, if using Serials module, please see Security Notice
Already running 2.0:
Coming from 1.6.1:
If you are currently on a version before the latest one, make sure you follow the upgrade instructions for all previous releases up to the version prior to latest before proceeding to the latest version.