Via Windows Blog, Microsoft as announced a new Windows Server build, via Fast Ring under the Windows Insider Program with the number 17074 . Behind the usual bug fixes, this build has a few new changes and functionalities.
One of the new content in this build is the In-place OS Upgrade. Now, costumers are able to upgrade their Windows Server, version 1709 installations to the current preview build using In-place OS Upgrade.
By running setup.exe, the option to “Keep personal files and apps” will be able, so, you don’t need to backup your information for the upgrade.