Windows Server 2016 - Can't RDP on server due to an error in the licensing protocol

Question

Hi,

I have a Windows Server 2016 with the following roles installed:

• Remote Desktop Licensing
• Remote Desktop Session Host

The configuration is similar to this:
https://learn.microsoft.com/en-us/troubleshoot/windows-server/remote/install-rds-host-role-service-without-connection-broker

Added the CAL (per user) license and RDS server is activated. Group Policy objects configured accordingly.

Configuration seemed to work fine until my last server reboot. Now my users can't connect over RDP and they are getting this error message:
The remote computer disconnected the session because of an error in the licensing protocol. Please try connecting to the remote computer again or contact your server administrator.

The only method I can get in is in console mode (bypassing the installed CALs) by using the mstsc /admin switch.

I'm all out of ideas. Any suggestions / hints on how to fix this would be highly appreciated.

Thanks in advance,
bmocanu

Answer 1

Hello @bmocanu

When using per-device CALs, RDP needs to write a license to
HKEY_LOCAL_MACHINE\Software\Microsoft\MSLicensing and if it cannot, then you will get this message.

Logged on as standard user does not have rights to write to registry location, whereas running RDC as administrator ensures that the app has the required permissions to modify the Registry.

You may try delete the two folders underneath "hardware id" and "store" on client machine:

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\ Microsoft\MSLicensing\HardwareID
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\ Microsoft\MSLicensing\Store

Then on the client, run "Remote Desktop Connection" as administrator (just one time), from then on, it can be run as usual.

However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, see How to back up and restore the registry in Windows.

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Best Regards
Karlie