Windows Server 2016 Build 14393970 Enus April — 2017 2021 =link=

As a cumulative update, Build 14393.970 focused on reliability and bug fixes rather than major new OS features:

If in 2021 you needed to patch a Server 2016 build earlier than 14393.970, you could not directly install a 2021 cumulative update. The April 2017 update introduced a new servicing stack version that became mandatory for later updates. Specifically: windows server 2016 build 14393970 enus april 2017 2021