Upgrading Unity SDK
Open Unity Package Manager under Window > Package Manager and check the Packages - coherence section. It will state the currently installed version and if there are any recommended updates available:
Unity Package Manager showing coherence installation
Follow the advice in this section in the order of releases, starting from the lower version. If you're upgrading by two or more major versions, it is recommended to first upgrade to the immediate next version, in case you miss any unrecoverable breaking changes.