Symptoms
Remote Desktop Service cannot be used in a mixed environment where Remote Desktop Connection Broker is installed on a Windows Server 2012/2012 R2 and a Remote Desktop Session Host is installed on Windows Server 2008 R2 or versions earlier.
An error will occur in the compatibility verification process when adding a Windows Server 2008, or earlier, Remote Desktop Session Host to a Windows Server 2012/ 2012 R2 Remote Desktop Connection Broker.
Cause
Windows Server 2008 R2 or versions earlier cannot be registered as a Collection in Windows Server 2012/2012 R2.
On Window Server 2008 R2, Remote Desktop (RD) Connection Broker manages in terms of “farms” which is a concept no longer in existence after Windows Server 2012.
A new concept of “collections” has been introduced in Windows Server 2012 which the RD Connection Broker manages in.
For the reasons above, RD Service cannot be used in a mixed environment where RD Connection Broker is installed on a Windows Server 2012/2012 R2 and a RD Session Host is installed on Windows Server 2008 R2 or versions earlier.
Resolution
It is reccommended to have a unified environment under the same OS version.
Workaround
None
