An upgrade replaces your existing operating system with a new one. This means that you retain your files and settings. This is often called an in-place upgrade because it happens in place on a machine with an operating system already installed. It is recommended that you make a backup of the Windows state, files, and folders before running an upgrade.
You can run an in-place upgrade to Windows Server 2019 if the actual server runs Windows Server 2016, Windows Server 2012/2012 R2, or Windows Server 2008 R2. However, Windows Server 2008 R2 can be upgraded to Windows Server 2019 in three consecutive upgrade processes—first by upgrading to Windows Server 2012, then upgrading Windows Server 2012 to Windows Server ...
