Occasionally Windows Server 2019 or Windows 10 will get "stuck" and not allow to change/register the product key.  To resolve, follow the steps below.


  1. Click Start and type CMD in the Start Search menu
  2. Right Click and choose Run as administrator
  3. To remove any existing product key (in case you used a trial key), enter and run the command slmgr.vbs /upk .
  4. Clear the product key from registry by running slmgr.vbs /cpky
  5. To enter your new product key, use the command: slmgr.vbs /ipk xxxxx-xxxxx-xxxxx-xxxxx where the x’s are your actual product key.
  6. Lastly, activate Windows by entering the command slmgr.vbs /ato
  7. Windows is now activated.

Source - https://technogecko.net/guides/change-product-key-does-nothing-windows-server-2019-windows-10-1809/