I just did a fresh Window 10 installation from .iso files on the computer I was running Windows 7 on before. I have the original Windows 7 DVD's, with a valid key that I was using before.

Now I tried to enter the key of my Windows 7 DVD, but Windows 10 says it's not valid.

As far as I knew we were able to use those Win 7 keys on Win 10. What is wrong?


6 Answers 6


Unfortunately, you must upgrade an existing installation before you are able to do a clean install of Windows 10. It is only once an upgrade has been done that you have a Windows 10 license at all.

After an upgrade has been performed that PC is licensed to use Windows 10 and a clean install can be done. During the clean install the product key entry should be skipped (multiple times if required) - the PC will still automatically activate when installation is complete.

From what I understand Windows considers the motherboard to be the PC for the purposes of licensing, as long as the motherboard is the same the PC is licensed for Windows 10

For more detailed information on performing a clean install, see this article.

In light of some of the confusion around this it's worth pointing out that although a lot of the Windows 10 licensing messaging has been unclear, the upgrade first requirement for clean installs has been something Microsoft have been talking about for as long as they have been talking of Windows 10 clean installs - so the system is "working as intended". It is, of course, entirely possible that Microsoft will create a new system for this soon, but for now this appears to be the only option.

Note that currently some people are having trouble activating Windows 10 despite having legitimate versions - these problems seem to resolve themselves in time

Edit: Removed unnecessary information about retrieving product keys

  • 1
    Ok thank you. So my only option now would be to format again, install Windows 7 again, "upgrade" that version. Then format again, do my clean installation of Windows 10, on which then my Windows 7 Key would work? Or I pay 199 USD and buy a new key. Correct?
    – Mr.Boon
    Commented Jul 29, 2015 at 11:48
  • 2
    Nearly. You will have a new and different Windows Product Key after upgrading to Windows 10. While it's possible this will be the same as your Windows 7 key it is unlikely, instead you will have a different Windows 10 only key which can then be used for doing a clean install of Windows 10. After upgrading to Windows 10, run the command above to find your product key (alternatively, a web search for "windows product key" will provide other methods for finding the key). Other than that, yes, you are correct. Commented Jul 29, 2015 at 12:15
  • 1
    This command only returns a key if you have an OEM device with an embedded key. The description of this command, "Product key from the OA3 BIOS marker", would indicate that if you don't have an embedded key it would return the string "OA3xOriginalProductKey".
    – Ramhound
    Commented Jul 29, 2015 at 23:41
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    As of November 21, can anyone confirm if this problem still exists? I had the small windows 10 icon in my windows 7 bottom right corner for many months, and I just got the message "Your upgrade is reserved" each time I went to Windows Updates to check for the upgrade. This morning, I used the media creation tool(from the MS Site) to upgrade. It all worked well. Then when I went to key-in my Windows 7 serial key in the newly installed Windows 10, it said - "this key is not valid. enter a different key". Any solution to this today? Also, will there be any future problem if I use it w/o the SK? Commented Nov 21, 2015 at 20:29
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    "Unfortunately, you must upgrade an existing installation before you are able to do a clean install of Windows 10." - This is no longer true. answers.microsoft.com/en-us/insider/wiki/…
    – cp.engr
    Commented Jun 23, 2016 at 2:59

The rules are changing...

Up til now, to qualify for your free upgrade to Windows 10, you were required to successfully complete an upgrade on a qualifying machine before you could then perform a clean install of Windows 10.

As from Insider Preview Build 10565 you can now activate using an existing Windows 7, 8 or 8.1 key which was previously used on that machine.

From the Windows blog by Gabe Aul - Announcing Windows 10 Insider Preview Build 10565

Device activation improvements: We have received a lot of feedback from Insiders on making it easier to activate Windows 10 on devices that take advantage of the free upgrade offer to genuine Windows by using existing Windows 7, Windows 8 or Windows 8.1 product keys. If you install this build of the Windows 10 Insider Preview on a PC and it doesn’t automatically activate, you can enter the product key from Windows 7, Windows 8 or Windows 8.1 used to activate the prior Windows version on the same device to activate Windows 10 by going to Settings > Update & security > Activation and selecting Change Product Key.

If you do a clean install of Windows 10 by booting off the media, you can also enter the product key from prior Windows versions on qualifying devices during setup. Refer to the Insider Hub for more information on these activation improvements including requirements.

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..and breaking news [which I hope to keep updated with more official sources, once known] which includes the same activation information
Windows 10 Fall Update is Set for November Release

  • That hasn't happened yet tho
    – Journeyman Geek
    Commented Oct 21, 2015 at 10:34
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    It does currently require you to be an insider but - though only an opinion - it would be unlikely that they would then remove this addition from the final release.
    – Tetsujin
    Commented Oct 21, 2015 at 10:38
  • Not sure why, but the ISO of build 10565 is no longer available. Microsoft removed that ISO from their Media Creation Tool website: These downloads cannot be used to update Windows 10 PCs to the November update (Version 1511). Very annoying since I want to do an update of my HW (SSD) when doing a clean Win10 install. This should be possible with build 10565 but if there is no ISO for download any longer, this becomes difficult. See also neowin.net/news/….
    – SaeX
    Commented Nov 22, 2015 at 12:38
  • That will be rather irritating for the thousands of people for whom the Windows Update just isn't working [including me, on 2 totally different machines]
    – Tetsujin
    Commented Nov 22, 2015 at 13:04
  • 1
    ...& it's back...
    – Tetsujin
    Commented Nov 27, 2015 at 10:04

Earlier this month I did a clean install of Windows 10 Pro build 1067 on a Hewlett Packard G6 laptop, using the Windows 7 key off the COA when prompted during install.

I also have a Lenovo laptop that it looks like I'm going to have to start over on because it's rejecting the COA Win 7 key after Windows 10 is installed.

Microsoft is still accepting Windows 7 and Windows 8 keys for 10, but for some reason only during install - though while searching for if it's possible to make it take the key post-install - it looks as though MS is not accepting ALL Win 7 COA keys.

So if you have a computer that came with an OEM install of 7, 8 or 8.1, try the COA key while installing 10. It'll either work, or not. If it works you save the bother of installing Windows twice then cleaning up after the upgrade, or wiping it and installing Windows a 3rd time.


In case of a hardware change

In situations such as after changing your motherboard, which everybody believes the Windows 10 upgrade license activation process is tied into, you need to

  1. Install the original Windows 7/8 again and activate it with your original Windows 7/8 license,
  2. Either do the Windows updates to get the Upgrade to Windows 10 notification (specifically KB3035583 update), or burn the ISO file for Windows 10 into a DVD and install it (Choose upgrade, not the fresh install) from within your original Windows 7/8. (Note 3)

The process above will register your new hardware against your free Windows 10 license (Upgraded from Windows 7/8). Now you can do a fresh install of Windows 10 and skip all the License Key (two of them I believe) during the installation process and it's guaranteed your Win 10 will be active after the end of this process.

Note: Since my Windows 10 was already set up (However showing me no Activated after the hardware change) and in a working state, I have done the steps 1 & 2 on a separate HDD, which lead to registering my new hardware with the Win 10 license and then plugged the original HDD back on with my configured Win 10 and it was activated after this process. Then I didn't need to set up my Windows from the scratch again.

Note 2: I have contacted Microsoft and they couldn't activate the Win 10 on the new hardware and recommended the steps 1 & 2.

Note 3: Be reminded that step two is only going to be active till July 2016 and after that, you won't be entitled to a free upgrade of Windows 7/8 to Windows 10 anymore.


The key must have been activated with the original version of Windows it was tied to. In case if you upgraded to Windows 10 say by a clean install without having first activated the original version of Windows with the key then you will have to go back i.e. reinstall the old version and activate first.


For OEM software license holders, it seems the solution is to install Windows 10 first (fresh or not) and bypass the key input screen. Once Windows 10 is installed goto Settings -> Update & Security -> Activation -> Change Product Key then you ender your OEM key and it should work. I'll test this myself soon.

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