Issue :

• VDA is unregistered showed with incompatible OS (hence users will not be able to launch their desktop)
• Warnings seen in Event logs:

Instructions

• On the Master Image ran the VDA Clean Up utility, to uninstall the VDA
  Ref: https://support.citrix.com/article/CTX209255
• After the reboot and completion of the cleanup utility configured the server for VDI installation as under:
  (Launched ServerManager from Comandline as it was not launching from the administrative tools)
  ref: http://docs.citrix.com/en-us/xenapp-and-xendesktop/7-12/install-configure/server-vdi.html
  • Uninstalled Remote Desktop Services role (which might have been installed with the Server VDA installation done before)
  • Verified that  ‘Restrict each user to a single session’ property is enabled. It is set using the below registry key
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TerminalServer
    Name: fSingleSessionPerUser
    Type: Dword
    Value: 1
• Using the command line installed the VDA. The VDA set up is located at the below location in the installation media:
  "\x64\XenDesktop Setup\" (The Server VDA is used with the specific switch and NOT the Desktop/Workstation VDA)
  1. Open the CMD as an administrator
  2. Browse to the above location of XenDesktopVdaSetup.exe
  3. Run the command: XenDesktopVdaSetup.exe /quiet /servervdi /controllers FQDN_COntroller1,FQDN_Controller2 /enable_hdx_ports
• Use switch /masterimage if the VDA will act as a Master Image for MCS or PVS
• This will take a couple of minutes and install the VDA
• The machine will automatically reboot once the installation completes