Cannot activate Windows 10. Product Key blocked.

If when you try to activate Windows 10, you receive an error message that Windows 10 couldn’t be activated, then this post may help you. Maybe you upgraded to Windows 10 or maybe you did a clean install of Windows 10 – or then maybe your Windows 10 blocks product key, even after upgrading first & then clean installing the OS.

Windows 10 product key not working

The way to go about this is Upgrade your Windows 7 or Windows 8.1 to Windows 10. Ensure that it is activated and then if you wish, clean install Windows 10 on the same device. If you directly clean installed Windows 10 and then used your earlier key, it will not work.

Cannot activate Windows 10

Cannot activate Windows 10

If you upgraded to Windows 10 for free from Windows 7 SP1 or  Windows 8.1 Update and ended up with a non-activated Windows 10, try this:

Open Settings app > Update & security > Activation. Select Go to Store, and check if a valid license is available for your device. If a license isn’t available, you’ll need to buy Windows from the Store. This post will show you how to check Windows 10 activation status, activate it, or change the product key.

If your key is not accepted and activation fails, then in such scenarios, you may receive error messages like:

The activation server determined the specified key is blocked

Windows can’t activate right now. Try again later

We couldn’t activate Windows

Windows Activation failed

Windows Activation fails

If you have tried to activate your copy of Windows over the Internet, and failed, with perhaps any of the following error codes, like with error code 0x80004005 or 0x8004FE33, you may want to follow this Windows Activation fails tutorial.

Microsoft has also described a few scenarios. See which one applies to you and follow the suggestions made.

Error 0xC004F061 – You upgraded to Windows 10, but didn’t have a previous version, or the correct edition of Windows installed

If you see error 0xC004F061 when you try to activate Windows 10:

You’re using a product key to upgrade to Windows 10, but a previous version of Windows wasn’t installed on your PC. To update, you need to have Windows 8 or Windows 7 already on your PC.

If you formatted or replaced your hard drive, you wouldn’t be able to use a product key to update to Windows 10. You’ll need to install your previous version of Windows, and then reinstall Windows 10.

Error 0xC004C008 – One copy of Windows might have been installed on multiple PCs

If you have one copy of Windows and installed it on more than one PC, activation might not work because the product key has already been used on another PC, or it’s being used on more PCs than the Microsoft Software License Terms allow.

If your product key is being used on more PCs than the Microsoft Software License Terms allow, you’ll need to buy a new product key or the copy of Windows for each of your PCs in order to activate them.

A different version of Windows or the product key might have been used as part of a repair

If you took your PC to a repair shop or to someone who builds and fixes PCs, it’s possible that a different version of Windows was installed to complete a repair. Or, if a different product key was used for your PC during the repair, that key might be blocked if it was used on more PCs than the Microsoft Software License Terms allow.

If Windows was activated before your PC was repaired or rebuilt, then re-entering the product key that came with your PC or original copy of Windows might solve the problem. You can also try reinstalling your original version of Windows.

Hardware changes

If you made substantial hardware changes to your PC, like replacing your motherboard, Windows would not be activated on your PC.

Counterfeit software

If you have a counterfeit copy of Windows that wasn’t published and licensed by Microsoft, activation won’t work because Microsoft won’t be able to create a match between your PC’s hardware profile and your 25-character product key. Find out if your copy of Windows is counterfeit.

Used PC

If you bought a used PC with Windows already installed on it, it’s possible that the product key is being used on more PCs than the Microsoft Software License Terms allow.

Windows 10 Product Key blocked

Windows 10 product key not working

If Windows 10 blocks your product key, even after upgrading first & then clean installing, then we have a few suggestions to make:

  1. Uninstall the product key. Then enter the product key anew and try again. Use another key and see.
  2. Rebuild the Tokens.dat file. The Tokens.dat file in the Windows operating system is a digitally signed file, which stores most of the Windows activation files. Sometimes the Tokens.dat file may get corrupted as a result of which Windows Activation may not take place successfully.
  3. Open an elevated CMD and run Dism /Online /Cleanup-Image /RestoreHealth to repair the system image. Then try again.
  4. Activate Windows 10 by Phone.

I hope something here helps you.

This list of Windows 10 Activation errors and Windows 10 Upgrade & Installation errors may help you further troubleshoot the issue. Try the Windows 10 Activation Troubleshooter and see if it help you. Advanced users may want to see how to troubleshoot Windows Activation states. See this post if you receive The product key entered does not match any of the Windows images available for installation message during installation.

If nothing helps, you may want to use the built-in Contact Support app to contact Microsoft Support.

Now read about Digital Entitlement and Product Key Activation methods in Windows 10.

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Anand Khanse is the Admin of, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.