Oh this is not a fun one. I am doing a lot of domain controller maintenance on one of the many Windows active directory domain I manage and I noticed a little problem with replication on one of the domain controllers in the forest.
For those of you not familiar with NtFRS, according to Wikipedia, “File Replication Service is a Microsoft Windows Server service for distributing folders stored in the SYSVOL shared folder on domain controllers and Distributed File System (DFS) shared folders. It is also known as NTFRS after the name of the executable file that runs the service. This service is part of Microsoft's Active Directory.”
The error that I kept seeing was right after the file replication service was trying to start, and it would say:
Event Type: Error
Event Source: NtFrs
Event Category: None
Event ID: 13559
Time: 9:19:05 PM
The File Replication Service has detected that the replica root path has changed from "c:\ad\sysvol\domain" to "c:\ad\sysvol\domain". If this is an intentional move then a file with the name NTFRS_CMD_FILE_MOVE_ROOT needs to be created under the new root path.
This was detected for the following replica set:
"DOMAIN SYSTEM VOLUME (SYSVOL SHARE)"
Changing the replica root path is a two step process which is triggered by the creation of the NTFRS_CMD_FILE_MOVE_ROOT file.
 At the first poll which will occur in 60 minutes this computer will be deleted from the replica set.
 At the poll following the deletion this computer will be re-added to the replica set with the new root path. This re-addition will trigger a full tree sync for the replica set. At the end of the sync all the files will be at the new location. The files may or may not be deleted from the old location depending on whether they are needed or not.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
You know what though? The fix is actually pretty easy. All you have to do is browse to the directory that is mentioned in the error. In the above case it is c:\ad\sysvol\domain right click in there and create a new text file called NTFRS_CMD_FILE_MOVE_ROOT with no extension. After that, the error will go away, and replication should continue again within a few minutes.
Did that help you with your issue? Are you experiencing another replication issue? Maybe we can help. Hit us up in the comments!