Explanation
AD FS for Windows Server 2016 introduces the ability to have separation between server administrators and AD FS service administrators.
After upgrading our ADFS servers to Windows Server 2016, the last step is to raise the Farm Behavior Level using the Invoke-AdfsFarmBehaviorLevelRaise PowerShell cmdlet.
To upgrade the farm behavior level from Windows Server 2012 R2 to Windows Server 2016 use the Invoke-ADFSFarmBehaviorLevelRaise cmdlet.
References: https://technet.microsoft.com/en-us/library/mt605334(v=ws.11).aspx