Microsoft has released Windows Server Insider Preview Build 17079 to Windows Server Insiders

What’s New in Build 17079 for Windows Server
In-place OS Upgrade: Customers are now able to upgrade their Windows Server, version 1709 installations to the current preview build using In-place OS Upgrade. This feature is available starting in build 17079. This feature also enables customers to perform build-to-build upgrade of the next released preview build.

Running setup.exe, customers should be presented with the option to “Keep personal files and apps”, which causes the migration steps in setup.exe to run and upgrade Windows Server while preserving applications, data, and user settings.

Please refer to the Known Issues section below for additional information.

Known issues with Windows Server build 17079
[NEW] When Hypervisor Code Integrity (HVCI) is enabled, a system may fail to start. On affected systems, firmware locates UEFI runtime services in memory described as Memory-Mapped I/O (MMIO).
Running nanoserver-insider containers on a Windows Server Core host will fail, and may crash the host.
As a workaround, you can add “—isolation=hyperv” when running or building the containers such as “docker run –isolation=hyperv microsoft/nanoserver-insider”.

  Windows Server Insider Preview Build 17079 released