Windows 10: EC: 0xC004C003 - cannot activate windows after upgrading to Windows 10

  1.    02 Oct 2015 #1

    EC: 0xC004C003 - cannot activate windows after upgrading to Windows 10

    So long story short....

    I had to get a replacement SP3. I have been running Windows 10 since January on my old SP3. When I received my new SP3, it came with W8.1 Pro. wasn't getting the upgrade option so I thought "hey why don't I just install x10162 then update it". So I did a clean custom install, upgraded to 10162, then updated to 10547. That is what I am running now, and it works great. only problem I am having is to activate windows.

    I downloaded the RTM, thought I could clean install that, and punch in my 8.1 product key... no luck.

    Any advice from anyone?

      My ComputerSystem Spec

  2.    02 Oct 2015 #2

    You need a successful activation of the upgrade to Win10 first. If you are done with Insider builds (not a can of worms I'm versed in), go back to Win 8.1 Pro, make sure it's activated, and proceed with free upgrade to Win10 Pro and it should activate - confirm activation of the upgrade before doing a clean install (then not needing product key, you "skip" or "next" that) if you expect that to activate.

    Means of upgrading vary from Windows Update to dowloading the media and burning to a bootable DVD or USB key.

    Depending on your technical inclinations, there is also a Tutorial here for going straight from activated Win 8.1 Pro through to a clean install of Win10 Pro that activates.
      My ComputerSystem Spec

  3.    02 Oct 2015 #3

    What is the best way to go back to Win 8.1 Pro? Since I don't have a recovery on my SSD. Thanks
      My ComputerSystem Spec

  4.    02 Oct 2015 #4

    Assuming your 8.1 Pro license is limited to O.E.M. privileges as it came with the SP3, and that the on-board recovery mechanism is gone, the best way would be to see if you can get install/recovery media from the manufacturer. Check this link:
      My ComputerSystem Spec

  5.    02 Oct 2015 #5

    Why not just download the Windows 8.1 Pro ISO and install from that?
    Create installation media for Windows 8.1 - Windows Help
      My ComputerSystem Spec


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