KB5008207

After installing updates released April 22, 2021 or later, an issue occurs that affects versions of Windows Server that are in use as a Key Management Services (KMS) host. Client devices running Windows 10 Enterprise LTSC 2019 and Windows 10 Enterprise LTSC 2016 might fail to activate. This issue only occurs when using a new Customer Support Volume License Key (CSVLK). 

Note This does not affect activation of any other version or edition of Windows. 

Client devices that are attempting to activate and are affected by this issue might receive the error, "Error: 0xC004F074. The Software Licensing Service reported that the computer could not be activated. No Key Management Service (KMS) could be contacted. Please see the Application Event Log for additional information."

Event Log entries related to activation are another way to tell that you might be affected by this issue. Open Event Viewer on the client device that failed activation and go to Windows Logs > Application. If you see only event ID 12288 without a corresponding event ID 12289, this means one of the following:

• The KMS client could not reach the KMS host.

• The KMS host did not respond.

• The client did not receive the response.

For more information on these event IDs, see Useful KMS client events - Event ID 12288 and Event ID 12289.

This issue is resolved in KB5010359.

After you install this update on a server that is running Windows Server 2016, you might not be able to use Remote Desktop to reach the server. Eventually, the server might stop responding. Additionally, a black screen might appear, and signing in and general performance might slow.

This issue is resolved  in KB5010195.