I've just upgraded my activated Windows 7 Professional to Windows 10 Pro.
I upgraded, rather than making a fresh install.
During installation I was asked for the product key, it wasn't accepted, so I proceeded without the key. Now when I try to activate I get this error:
You are running Windows 10 Pro. The Product key you entered cannot be used to activate this edition. Error Code: 0xc004f210
I looked into similar questions like this and this, but the difference is that I upgraded (rather than doing a fresh install) from Win 7 professional to Win 10 pro. I don't mind reinstalling win 7 and doing it all from scratch again. But I was wondering if there was an easier way.