Check the product key and try again or enter a different one.”Īs you already might know, Microsoft had permitted Windows 7, Windows 8, and Windows 8.1 users to upgrade to Windows 10 without having to pay a penny. You will see an error message “ The product key you have entered didn’t work. This error shows up when trying to enter the genuine Windows 10 product key via the control panel. If you recently bought a used Windows computer with an older version of the operating system (Windows 7, Windows 8, or Windows 8.1), you are likely to run into the infamous 0xc004f050 error.
