FRS, what? That was replaced by DFSR back in Windows 2008. Yes it was replaced and I have been finding FRS still in use at various environments. If your domain was once at 2003 functional level, then you might be running FRS and Windows 2016 SR2 + doesn't support FRS. This article shows you how to check to see if you are running FRS for SYSVOL replication and how to migrate to DFSR. Trust me, it is easy.
Microsoft 2008, 2008 R2 Server
Microsoft Windows 2012, 2012 R2 Server
Microsoft Windows 2016 Server
How to Verify What Replication Method is in Use
One method is to see if the service File Replication Services is enabled and running. If it is, you are using FRS.
Another method is to open a command prompt as an administrator and run the command dfsrmig /GetGlobalState. If the message DFSR migration has not yet initialized, you are using FRS.
How to Migrate from FRS to DFSR
Verify the domain functional level. The domain functional level must be at least 2008. To do this, either use Active Directory Users and Computers, or from an elevated PowerShell window with Active Directory modules loaded enter Get-ADDomain and look for DomainMode.
Verify SYSVOL is healthy and replicating correctly between all domain controllers. If there are any replication issues, you must resolve them before continuing.
Once you have verified or set the domain functional level to at least 2008, we can start the migration process. Open a command prompt as an administrator and run the command dfsrmig /CreateGlobalObjects. This command creates the needed objects for DFSR within AD.
If you have domain controllers at different sites, you will have to wait for AD replication for all domain controllers. To view the status run the command dfsrmig /GetMigrationState. This will tell you if the domain controllers are ready to proceed to the next step or if replication hasn't occurred yet.
Once replication has completed and is verified through the command dfsrmig /GetMigrationState, run the command dfsrmig /SetGlobalState 1. This command prepares the domain controllers for DFSR.
You will have to wait for AD replication to complete for all domain controllers. You can view the state by running the command dfsrmig /GetMigrationState.
Once replication has completed and is verified through the command dfsrmig /GetMigrationState, run the command dfsrmig /SetGlobalState 2. This command redirects SYSVOL to SYSVOL_DFSR within C:\Windows.
You again have to wait for AD replication to complete for all domain controllers, and again you can view the state by running the command dfsrmig /GetMigrationState.
Once replication has completed again. You now come to the point of no return. Up until now, you can revert back. But the next command commits you to DFSR. Don't worry, if everything has been fine so far, there is nothing to worry about. Run the command dfsrmig /SetGlobalState 3. This command will remove SYSVOL from C:\Windows.
You have to wait for AD replication this last time and again you can use the command dfsrmig /GetMigrationState. Once replicated, you are now using DFSR to replicate SYSVOL!