I originally had Windows 8.1 Pro installed on a machine. This was upgraded to Windows 10 Pro a while ago.

Unfortunately last night my OS SSD died and I've just installed a new one and installed Windows 10.

According to this Microsoft Article I need no Product Key as Windows will automatically activate online.

I have linked the new Windows 10 installation to the same Microsoft account but I'm still unable to get Windows to activate.

I had written down the product key as shown to me by the previous Windows 10 installation but that starts with two 0s which you can't even type into the product key box as it reports as an invalid character.

Has anyone else gone through this process and successfully activated Windows 10?

I'm worried if the change in hardware is the issue ... surely this is a very common scenario for the need to reinstall Windows?


So after a number of calls with Microsoft with varying success of actually completing a call without being cut off. I was given the following workaround:

  • Install Windows 8 Pro
  • Activate
  • Apply all 8 updates (153)
  • Upgrade to 8.1 Pro
  • Apple all 8.1 updates (31)
  • Run media creation tool to update to Windows 10
  • Apply all Windows 10 updates

Yup, install all 3 OSs. Kinda cheaper to just buy a license if this was on work time ...

  • You changing your HDD wouldn't have caused a hardware hash change. So in the future all you have to do is install Windows 10, since I assume now, the installation is activated. Furthermore, if you originally had Windows 8.1 you could just install that then upgrade to Windows 10. You could also just upgrade from Windows 8 to Windows 10 since if you are doing that you have nothing to keep. – Ramhound Sep 20 '15 at 23:10
  • 1
    MS Support told me that a change in HDD would change the hash, hence having to go all the way back to Windows 8 and upgrade through 8.1 to 10 again. – Jammer Sep 21 '15 at 10:00
  • You were told incorrect information. If you already had Windows 8.1 installed then there is no reason to install Windows 8, which accepts and activates, with Windows 8.0 licenses ( just doesn't install with them ). – Ramhound Sep 21 '15 at 10:20
  • Hmm ... out of the 6 calls to MS 4 of them simply were cut off. Not that impressed to be honest. – Jammer Sep 21 '15 at 13:50

I had Windows 7 Genuine installed and made the mistake of doing a clean install of Windows 10 versus doing an upgrade.

~2 Hours or more of being on the phone with 3 tiers of Microsoft Support:

I eventually was told by support staff the only way they can provide a Windows 10 key is if I have some sort of proof of purchase for the old Windows.

In your case, since you have your Windows 8.1 Product key you should get in touch with support and they should be able to generate you a Windows 10 key based from it.

  • Seems there is a lot of varying stories on this. I just got off the phone with Microsoft and I've been told to reinstall Windows 8, activate that, then upgrade to 8.1 then upgrade that to Windows 10. Talk about convoluted and obtuse. – Jammer Sep 19 '15 at 12:20
  • Oh they gave you the workaround way. I seriously had a case number I could call in to and say "found my product key!" for them to generate me a new Windows 10 key. Hopefully you get everything working. – Insane Sep 19 '15 at 18:39
  • I'm up and running again, no help from MS. Ended up on their support line 5 times, 3 times of which I was cut off after spending nearly 30 mins each time. – Jammer Sep 19 '15 at 19:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.