KB: Connection hangs after you import virtual machines into Windows Server 2012 Remote Desktop Services Unmanaged Pool

New KB article (2891541) related to migrating Windows Server 2008 (R2) VDI VM’s to Windows Server 2012.

“…Consider the following scenario:

• You have a Virtual Device Interface (VDI) infrastructure that is configured on a server that is running Windows Server 2008 or Windows Server 2008 R2.
• You have another Windows Server 2012 VDI environment.
• You migrate virtual machines from Windows Server 2008 or Windows Server 2008 R2 to the Windows Server 2012 VDI environment.
• You import the virtual machines into Windows Server 2012 Remote Desktop Services Unmanaged Pool.

In this scenario, if you try to connect to a virtual machine from Remote Desktop Web Access (RD Web) or Remote Desktop Protocol (RDP), the connection stops responding (hangs) at the "Loading the virtual machine" state. Additionally, the connection may time out, and you receive the following error message:

Connection processing has been canceled. Try connecting again, or contact your network administrator…”

“…The problem occurs because Windows Server 2012 VDI virtual machines add a Remote Desktop Virtualization (RDV) device that does not exist in virtual machines that are not created by using Windows Server 2012. Without this device, the VDI RDP client cannot connect to the virtual machines, and the connections hangs…”

“…To work around this problem, re-create the virtual machines in Windows Server 2012 and copy over the Virtual Hard Disk (VHD) instead of exporting and importing the virtual machines…”

Source: http://support.microsoft.com/kb/2891541/en-us?sd=rss&spid=16526