If a MAK activation key is erroneously applied to a multi-session Windows 10 EVD (deployed from Azure Marketplace) the OS will not allow multiple users to connect at the same time. This can be repaired by re-setting to KMS activation with the proper Windows 10 EVD key.
Run the following commands from administrative command prompt:
- slmgr /ipk CPWHC-NT2C7-VYW78-DHDB2-PG3GK
- slmgr /ckms
- slmgr /skms kms.core.windows.net
- slmgr /ato
NOTE: These command cannot convert a single-session Windows 10 Enterprise OS to multi-session. This can only be used to repair what originally was a multi-session Windows 10 EVD OS.