How To Do A Clean Install Of Windows 8 With An Upgrade Disc

How To Do A Clean Install Of Windows 8 With An Upgrade Disc

Sometimes you just need to do a clean install. Unfortunately, the Windows 8 Upgrade can throw you an error when you try to activate the operating system afterwards. Lifehacker reader uncommoner shows us a workaround for this issue.

If you do a clean install using the Windows 8 Upgrade Assistant, you should be fine — but if you’ve already formatted your drive or you’re moving to a new drive, you can’t do a “clean install” without installing an old version of Windows first. It will let you install Windows 8 cleanly, but when you go to activate, you get error 0x8007007B, which says your product key can only be used for upgrading.

If you get that error, here’s how to fix it:

  1. Press the Windows key and type regedit. Press enter to open the Registry Editor.
  2. Navigate to HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/ and double-click on the MediabootInstall key in the right pane.
  3. Change the key’s value from 1 to 0.
  4. Exit the Registry Editor, press the Windows key again, and type cmd. Right-click on the Command Prompt icon and run it as an administrator.
  5. Type slmgr /rearm and press Enter.
  6. Reboot Windows.

When you get back into Windows, you should be able to run the Activation utility and activate Windows as normal without getting an error. Obviously, you could use this trick for evil, but it has its legitimate place too — if, say, you’re upgrading your hard drive and want to do a fresh install on it, or if you formatted your drive before upgrading.

We haven’t had a chance to test it ourselves, but it’s well-documented around the net, so we’re confident it should work for you if you’re getting this particular error. If you give it a shot, let us know how it works for you in the comments below. Thanks for the tip, uncommoner!


  • This method was used for awhile when Windows 7 came out but was quickly fixed by MS, so I think it will happen again with 8. Personally I just double install the upgrade version, which works OK, you just need to delete the window.old file. If you have trouble getting rid of the Windows.old folder just right click on the c drive and use disk cleanup.

  • Yep same you just boot from the disk type in your upgrade license key and then when installation is done start the upgrade process with the option to wipe every thing.

  • I just did this and it works as stated. After the untimely demise of my i7 920, I rebuilt my PC with new CPU and motherboard and Windows 8 refused to activate. It complained that my key was in use on another PC (the CPU in the bin). So I decided to do a clean reinstall as I was having driver issues and was unsure if it was my Win7-Win8 upgrade or the change to the new motherboard. I used this trick to save myself having to install Win7 first. I then activated Windows over the phone with a very nice Indian fellow. It’s all zipping along nicely now.

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