You’ll receive an error and won’t be able to promote Windows Server 2019 to a domain controller if the domain you’re trying to join is still running File Replication Service (FRS) because it has been depreciated. You need to first convert to Distributed File System (DFS).
The link they offer for more information is here:
https://support.microsoft.com/en-us/help/4025991/windows-server-version-1709-no-longer-supports-frs
Which links to a streamlined migration plan here:
There is no downtime or operational impact when the migration completes successfully. See the linked documents for risks and regression plans if issues are experienced.
Jason works as a project specialist at an IT MSP in Pennsylvania, USA. He’s an IT/security professional with 20 years experience.