How to fix Windows 11 activation error code 0xc004c003

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Marie-Ange Demory
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If Windows 11 won't let you activate your copy, there are a few things you can try to fix the problem.

If you have recently upgraded to Windows 11 or reinstalled your operating system, you get a Windows activation error showing error code 0xc004c003. This problem typically occurs when the system tries to activate the operating system with an OEM activation digital product key.

Here are some troubleshooting tips to help you fix this error and activate your copy of Windows 11.



What are the causes of error code 0xc004c003 in Windows 11 Pro?

The license key component in Windows is responsible for accessing the registry hive and verifying the product key. When access is denied due to incorrect login, it triggers error 0xc004c003.

A failed key validation can cause this error, but the reasons why it failed can vary. Here we explore some tips you can perform to fix this error in Windows 11.

Check your Windows version

Windows 11, like its successor, is available in multiple editions: Home, Pro, and Enterprise. Most consumer grade computers come with the Home edition already installed.

Depending on how you have installed Windows 11 on your PC, the edition of the installed operating system may change. If you have performed an in-place upgrade, Windows will automatically detect your existing edition and install the correct edition (Home, Pro, or Enterprise).

However, if you did a clean install for Windows 11, you might have installed the Pro edition instead of Home. Unfortunately, you won't be able to activate the Pro Edition with a Home Edition license key.


To check which edition of Windows 11 is installed:

  1. Awards Win + I to open Settings .
  2. In the card System , scroll down and click Information are .
  3. In the right pane, scroll down to the Windows specifications section. Here locate the section Edition to view the edition of Windows 11 installed on your PC.
  4. If your edition of Windows 11 matches your previous edition, upgrade to correction three of following.

If you purchased a Windows 11 Home license key and installed the Pro edition, try downgrading.


Downgrade from Windows 11 Pro to Windows 11 Home

If you have upgraded to Windows 11 Pro edition with the Home Edition license key, activation error 0xc004c003 will occur.

There are two ways to deal with this problem: First, upgrade to the Pro version by making a new purchase or downgrade to the Home edition.

If you don't want to give yourself the luxury of a new upgrade, the process to downgrade from Windows 11 Pro to Home involves two steps. You must first edit the registry editor to prepare for the downgrade and then run the ISO installation file to complete the downgrade process.

Edit the registry to install Windows 10 Home

  • Awards Win + R to open Run.
  • Type regedit and do click su OK to open the registry editor. click on Yes when requested by the AUC.
  • In the registry editor, go to the following path. You can copy and paste the path into the registry editor for easier navigation:

    ComputerHKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersion

  • In the right pane, locate and double-click the value Product name .
  • In the pop-up window, type Windows 11 Home Single Language.
  • Do click su OK per salvare I modified it.
  • Then, locate and double-click on the value EditionID .
  • In the pop-up window, type CoreSingleLanguage.
  • Do click su OK per salvare I modified it.
  • Then, go to the following location in the registry editor:

    ComputerHKEY_LOCAL_MACHINESOFTWAREWOW6432NodeMicrosoftWindows NTCurrentVersion

  • In the right pane, look for the value Product name and change it to Windows 10 Home.
  • Do click su OK per salvare I modified it.
  • Then, locate and double-click EditionID and change it to CoreSingleLanguage.
  • Do click su OK per salvare I modified it.
  • Close the registry editor.

Downgrade a Windows 11 Home

To complete the downgrade process, we will download the ISO file and perform an in-place upgrade. An in-place upgrade lets you reinstall the Windows operating system without removing files or apps. Here's how to do it.



  • Go to Microsoft's official Windows 11.
  • Scroll down to the section Download Windows 11 Disc Image (ISO) .
  • Click on the drop-down menu and select Windows 11.
  • Click the button Download .
  • Then, select your language from the drop-down menu.
  • click on Confirmation .
  • Click the button Download a 64 bit . The download for the Windows 11 ISO will begin.
  • Once the ISO is downloaded, open the download folder.
  • Right-click the ISO image and select Various.
  • Windows will mount the ISO and automatically open the drive folder. If not, click the icon the DVD drive in This PC.
  • Inside the ISO folder, double-click the file Setup.exe . click on Yes if requested by UAC.
  • In the Install Windows 11 window, click Change how the installer downloads updates.
  • Then, click Not now.
  • click on NEXT per I will proceed.
  • Then, accept the license terms and notices.
  • In the window Ready to install , make sure the option Installa Windows 11 Home e Keep personal files and apps is displayed.
  • click on Install and wait for the process to complete. An in-place upgrade can take a few hours to complete, depending on your system hardware. You may also notice some reboots during the process, but this is normal behavior.

After the reboot, check if the downgrade was successful. To do this, go up Settings> About> Windows Specifications and check the edition.


To activate Windows 11, go to Settings> System> Activation. Then, follow the onscreen instructions to activate your Windows 11 edition.

Activate Windows 11 using the command prompt

Sometimes, the Microsoft server may fail to verify and activate the license due to server problems. If the activation still fails, you can use the command prompt to activate your license. Here's how to do it.


  • Press the Windows key and type cmd .
  • From the search results, right-click Command Prompt and select Run as administrator. click on Yes if requested by UAC.
  • In the Command Prompt window, type the following command and hit enter:

    slmgr.vbs –rearm

  • When the success prompt is displayed, do click su OK and restart your PC. After rebooting, open the activation page and check if the 0xc004c003 error is resolved.

Contact Microsoft to reactivate Windows after a hardware change

When you register your Windows 11 license for the first time, it binds to your computer hardware. This helps Microsoft ensure that the license is used according to the terms of use and, furthermore, the user does not have to manually activate Windows every time after a clean installation.

However, if you've made any major hardware changes, such as replacing your motherboard, Windows won't be able to verify that they're valid. To fix this, you can use the digital product key or run the troubleshooter to verify and activate Windows. Check out Microsoft's resources on reactivating Windows 11 after a hardware change for additional troubleshooting steps.

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