Find a valid activation code for Windows 10 Pro on Windows 8.1 Pro.
Find a valid activation code for Windows 10 Pro on Windows 8.1 Pro.
The name implies you should stick to Windows 8.1 Pro keys, not Windows 10 Pro keys.
They were thinking about using an OEM key since it's more affordable compared to the official Win 10 keys.
It worked before, but I believe Microsoft removed that exception some time back. (Grr.)
The upgrade process was halted. You may only restart it if the same key was used for upgrading to Windows 10 or 11 before.