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Can't activate Windows. 0xC004C008

EUGEN TSIBULEVSKIJ 0 Reputation points
2025-12-14T19:20:23.0166667+00:00

I've bought a new PC and Windows disto with activation code included(packed and sealed with holographic lable). After assembly and windows installation i've tried to activate it using provided key. And i've got 0xC004C008 error.

I've got the distro from one of the biggest distributors in the country, so i doubt that it's fake. Also i'm pretty sure that i haven't used the key anywhere before. I just opened it 2 minutes before activation.

Here is what slmgr -dli gives me:

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Please, help

Windows for home | Windows 11 | Licensing and activation
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  1. Neil D 30,295 Reputation points Volunteer Moderator
    2025-12-14T22:36:43.38+00:00

    An OEM licence is meant to be used during the installation process as it is for a system builder.

    the only way to be sure is to clean install try the key when prompted.

  2. Norah-L 1,820 Reputation points Microsoft External Staff Moderator
    2025-12-15T08:12:41.8333333+00:00

    Welcome EUGEN TSIBULEVSKIJ to the Q&A forum.

    I understand you're running into the 0xC004C008 error when trying to activate your new Windows installation with the product key. This error typically indicates that the activation key you’re using has been used on another device or that it is being incorrectly processed by the system.

    Here are some steps you can take to troubleshoot the issue:

    1. Edition check: On the box or invoice for your key, confirm it says Windows Pro and that there’s no mismatch.
    2. Run the activation troubleshooter

    Open Settings > System > Activation.

    If Windows shows “Not active” or an activation error, there will be a “Troubleshoot” button; click it to start the Activation troubleshooter and wait while it checks your license and key.

    Follow any prompts it gives (for example, sign in with your Microsoft account or confirm this is the device to activate), then restart if it says changes were made.

    1. Try to activate by phone (if available) - recommended

    Start > Settings > System > Activation > Active Windows now > Activate by phone

    1. Even though you believe the key hasn't been used before, it may be worth checking with the distributor for verification.
    2. Contact Microsoft Support for direct support

    Hope one of these could help. I'm here if you need further details.

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