Windows server 2019 unable to connect to RD licensing host due to DCOM error

Question

Hello,

I have two windows 2019 servers VM's running in vSphere , server one is running remote desktop session host and server two is the remote desktop licensing manger. Server one is configured via local GPO's to connect to server two. But when providing credentials in RD licensing diagnoser on server one in order for it to connect to server two. it fails. I have tried providing both domain accounts with admin rights to both servers along with the local built in admin account for server two.

Both the provided domain account and the local account are able to log onto server two via RDP when testing.

checking the event log I can see the below error every time I try to provide credentials

DCOM was unable to communicate with the computer *server two* using any of the configured protocols; requested by PID     1718 (C:\Windows\system32\mmc.exe), while activating CLSID {8BC3F05E-D86B-11D0-A075-00C04FB68820}.

Read that UAC could cause a issue, this have been fully disabled on both servers and still have the same issue,

Both servers are also set to have default authentication levels of packet integrity and default impersonation level of identify under component services.

All other machines within the domain are able to connect to server two successful and are working as normal remote desktop session hosts.

List of installed updates on server one:

KB5034619

KB5028588

KB4512578

KB4512577

list of installed updates on server two:

KB5028588

KB5033904

KB5025229

KB4512577

servicing stack 10.0.17763.4121

any suggestions are appreciated as I am currently out of ideas

Answer 1

Hello,

Thank you for posting on the Microsoft Community forums.

First, ensure that the RD Licensing role is installed and the license server is activated correctly. Also, verify that the license server has a client access license (CAL) for each user and device that can connect to RDS.

Moreover, you can attempt the following troubleshooting steps:

1. You could try backing up and then removing the X509 Certificate registry keys, restart the computer, and then reactivate the RD Licensing server.
2. Check if the Remote Procedure Call (RPC) service is running on both servers. You can do this by opening the Services console and looking for the service named "Remote Procedure Call (RPC)".
3. Verify that the firewall settings on both servers are not blocking the communication between them. You can temporarily disable the firewall to test if this is the issue.

If the issue persists, you might want to consider rebuilding the RDS license server database.

For detailed instructions, please refer to the following article:

Cannot connect to RDS because no RD Licensing servers are available - Windows Server | Microsoft Learn

Hope this help. If you have any questions or concern, please feel free to contact us.

Regards,

Jacen Wang

Answer 2

Hello,

Thank you for posting on the Microsoft Community forums.

First, ensure that the RD Licensing role is installed and the license server is activated correctly. Also, verify that the license server has a client access license (CAL) for each user and device that can connect to RDS.

Moreover, you can attempt the following troubleshooting steps:

1. You could try backing up and then removing the X509 Certificate registry keys, restart the computer, and then reactivate the RD Licensing server.
2. Check if the Remote Procedure Call (RPC) service is running on both servers. You can do this by opening the Services console and looking for the service named "Remote Procedure Call (RPC)".
3. Verify that the firewall settings on both servers are not blocking the communication between them. You can temporarily disable the firewall to test if this is the issue.

 

If the issue persists, you might want to consider rebuilding the RDS license server database.

For detailed instructions, please refer to the following article:

Cannot connect to RDS because no RD Licensing servers are available - Windows Server | Microsoft Learn

Hope this help. If you have any questions or concern, please feel free to contact us.

Regards,

Jacen Wang

Hello,

thank you for your reply,

RD licensing server is set up correctly, there are 6 other session hosts that are connected successfully to this licensing server.

There are 103 2019 CALs left.

I've checked the "remote procedure call (RPC)" and this service is running on both the session host and on the RD licensing server.

the firewall is turned off on both the session host and the licensing server as they are in a isolated environment

I'm reluctant to rebuild or remove x509 cert as the license server as it is in a production environment and has 6 session hosts that are working fine.

The article you linked isn't related to the issue I'm having, I'm getting a DCOM error when trying to connect to the RD licensing server

Regards,
Cameron Smart

Answer 3

Sorry to hear your issue is still unresolved. I don't have your vSphere environment, but I suggest you navigate to Component Services -> Computers -> My Computers. Click "My Computer" and go to "Properties". Check the COM Security tab to confirm that the account has the necessary permissions.