Hello You are using a Windows 10 2019 LTSC MAK product key to activate Windows 10 2021 LTSC version, right? According to the error message, it seems the two version didn't share the same MAK product key. For a license issue, it is recommended to ask for help from the volume license center. https://www.microsoft.com/Licensing/servicecenter/default.aspx
Windows 10 IOT LTSC 2019 product key not working on Windows 10 IOT LTSC 2021
Nagre, Chanchlesh
0
Reputation points
We are currently using windows 10 IOT LTSC 2019 and we tried upgrading it to Windows 10 IOT LTSC 2021 and entered the same multi-user product key as used in 2019 version, but it is not accepting the key.
Error "This key doesn't work with this edition of windows. Try a different key.