I got a Windows 10 key and tried to do the normal upgrade, but got a "0xc004f050" error. I then tried to fix it by useing the generic pro key but then got a "0x803fa067" error. These are the steps the finally got everything working. I did the this on 2 PC so I think it is solid.
- buy a valid Windows 10 Pro key (any key will work)
- I got mine on Ebay for $4. It said 1 minute delivery, but it took about 1 hour to get it.
- Make sure Windows is up to date.
- Change product keys (remember these steps you will use them a lot)
- Select the Start button
- Then select Settings > Update & Security
- Then select Activation