Activating Windows Server(R), ServerStandard edition (6a4bd364-4b60-4856-a727-efb59d94348e) ...
On a computer running Microsoft Windows non-core edition, run 'slui.exe 0x2a 0x80072EE7' to display the error text.
This error occurs due to unavailability of KMS client activation key on the server.
Make sure to install the appropriate KMS client key (Based on the Edition of the OS) on the affected machine (KMS Client keys can be found
Open up elevated cmd (Run as Administrator) and execute following command
slmgr /ipk YC6KT-GKW9T-YTKYR-T4X34-R7VHC (Replace YC6KT-GKW9T-YTKYR-T4X34-R7VHC with right KMS client key)
Now, point your OS to the KMS server by running the following command
slmgr /skms KMS.domain.com (Replace KMS.domain.com with the FQDN of your KMS server)
Now, OS should get activated without any issues when you execute following command