*NOTE: Only follow these steps if you have a VALID Upgrade (I.e.: You legitimately own the previous full version you’re upgrading from)
This is what I did to solve the problem:
1. Do a clean install of Windows and do a keyless installation (I.e.: When it asks you to put in the key, just uncheck the “Validate Windows when I’m online” box and don’t enter the key; click “Next”)
Once you’re in Windows, you’re going to have to do some tweaking to “trick” it into letting you active Windows with the Upgrade key. To do this:
2. Once you’re at your desktop, run Command Prompt as Administrator (click Start, then type ‘command‘ in the Search box. You should see Command prompt on the list. Right-click it and click “Run as Administrator”. Click “Yes” on the Security Prompt).
3. At the command prompt, type: regedit
4. Once in Registry Editor, navigate to this key:
In that folder, look for the item MediaBootInstall
5. Double-click it and change the value to 0
6. Close out of Registry Editor. You should still have the Command Prompt open. Now, at the Command Prompt, type the following:
7. It should show something that tells you the command was successful.
8. Restart the computer. Then, go to the Activation screen (Click Start, Right-click Computer then click Properties. Scroll to the bottom and choose “Activate my copy of Windows”)
9. Enter your Upgrade product key and it should activate successfully!