Product activation net working online.

Question

Error code 0xC004C008.
Code already in use. This is a new laptop and the activation code is not working.
Please reactivate this key. We purchased this through an official Microsoft dealer.

We purchased 2 key's and both are not working.

Windows 11 Pro:

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__Please activate and let me know.

Harry ***

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***@colasit.nl

Answer 1

Dear Microsoft,

Phone activation isn't working. When I call, I immediately get a message that I need to activate via the website. aka.ms\aoh
So phone activation isn't working.

I've also contacted the vendor for clarification.
Everything else just leads to the same thing again, and you end up in a virtual loop.

Please Help

Answer 2

Hello Colasit,

Thank you for posting question on Microsoft Windows Forum!

Based on the provided error code 0xC004C008 which might indicate that the activation server has determined that the product key has already been used on the maximum number of devices allowed by the license.

Well! The first thing to do is to check the key type by using the command line slmgr.vbs /dli .Retail keys can usually be transferred to a new device, but OEM keys are tied to the first computer they are activated on. If your dealer sold you OEM keys, they will not work on a new laptop.

If it is a Retail key. You can use the Activation Troubleshooter by going to Settings → System → Activation. Select Troubleshoot. If you see an option like “I changed hardware on this device recently”, follow that path to reactivate.

On the other hand, try to use Phone Activation via slui 4 method. Press Windows Key + R on your keyboard. Type slui 4 and hit Enter. Choose your country/region and follow the phone prompts. You will get an installation ID to give to the automated system or support agent. For more information https://support.microsoft.com/en-us/windows/product-activation-for-windows-online-microsoft-support-product-activation-portal-35f6a805-1259-88b4-f5e9-b52cccef91a0

Otherwise, contact your official Microsoft dealer (where you bought the keys). Since authorized dealers have a direct line to Microsoft to "refresh" blocked keys or provide replacements if a batch was leaked or double-sold.

Hope the above information is helpful! If it is. Free feel to hit "Accepted" for benefitting others in community having the same issue too.

Answer 3

Error code 0xC004C008 indicates that the product key has already been used on another device or is being used on more devices than allowed by the Microsoft Software License Terms.

For Windows 11 Pro, the supported remediation steps are:

1. Confirm the error and run Activation Troubleshooter
   • On the new laptop, select Start > Settings > System > Activation.
   • Check that the error shown is 0xC004C008.
   • Select Troubleshoot (or use the Get Help troubleshooter via Run the troubleshooter in Get Help) and let it attempt automatic repair.
2. Try activating with the key as a new product key
   • In Settings > System > Activation, choose Change product key.
   • Enter the purchased Windows 11 Pro key and complete activation. This is effectively “activating again pretending as a new product key,” which has resolved similar cases.
3. If activation still fails with 0xC004C008
   • Use phone activation:
     • Press Windows key + R, type SLUI 04, and press Enter.
     • Select the country/region and follow the on-screen instructions to activate by phone.
   • If substantial hardware changes were made or if the keys are volume/organization keys, contact the organization’s IT admin or the official Microsoft dealer that supplied the keys and provide the error code so they can verify the license status and, if necessary, issue replacement keys.
4. If the keys were purchased as retail licenses directly tied to a Microsoft account
   • Sign in on the device with the same Microsoft account used for purchase.
   • Go to Settings > System > Activation and run the troubleshooter again so it can attempt to match the digital license to the new hardware.

If both keys consistently return 0xC004C008 on first use on new hardware, the dealer or Microsoft support must review the activation history and license entitlement; this cannot be reset or reissued from the device side alone.

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References:

• Get help with Windows activation errors
• Troubleshoot Windows activation error codes
• Reactivate Windows 11 - Microsoft Q&A
• Unable to use troubleshooter for windows activation - Microsoft Q&A
• Product activation for Windows - online & Microsoft Support Product Activation Portal