Microsoft has released a new build of the Windows Server vNext Long-Term Servicing Channel (LTSC) release that contains both the Desktop Experience as well as Server Core in all 18 server languages, as well as a new build of the next Windows Server Semi-Annual Channel release.

There are two major areas that we would like you to try out in each preview release and report back any issues:

In-place OS Upgrade (from Windows Server 2012 R2, Windows Server 2016)
Application compatibility – please let us know if any server roles or applications stops working or fails to function as it used to

  Windows Server 2019 Insider Preview Build 17666 released