The following error reportedly appears while activating your genuine copy of Windows 10.
Error 0xC004C003: The Activation server determined the specified product key has been blocked
Download the Diagnostic
There are certain situations when missing entries in your registry and registry corruption causes this problem. Try running a registry scan to identify if there are any such issues.
- Click the button below to download and install the Diagnostic
- Perform a Registry scan and fix any problems detected.
- Restart your computer.

Estimated Download Time: 10 Seconds
Reset the Computer
The process of resetting your PC involves cleaning up all third party programs downloaded from the Internet, installed from CDs and USB sticks. It uninstalls the operating system and all Windows Store apps; although they are reinstalled back again. You’ll be prompted whether to keep your documents and user files. Select the appropriate option.
1. Click Start; select the Settings.
2. Click Update & Security icon.
3. Click “Get Started” button under Reset this PC category.
Activate Safe Boot
The Safe Boot option in System Configuration utility also called as, Safe Mode, deactivates a significant number of Non-Microsoft programs that cause conflict with your computer. Windows will be loaded with a minimal set of system drivers and essential components.
1. Press Windows Key + R simultaneously.
2. Now you see the Run dialog box on your screen. Type “MSCONFIG” and click OK or press ENTER.
3. In the Boot tab, check-up “Safe boot” option, apply the changes and then restart.
Rename MSI Files
MSI files listed below are components of Windows Installer service. One or more component files are missing or corrupted. Do the steps given below to uninstall Windows Installer package and reinstall it again.
1. Open up the CMD as administrator. To do so, first open Start Menu, type “CMD” in Search Box. Right click the keyword in Search Results, select Run as administrator.
2. In the new window that opens, type following commands in sequence:
- cd %windir%\system32
- ren msiexec.exe msiexec.backup
- ren msi.dll msi.backup
- ren msihnd.dll msihnd.backup
3. Quit the Command Prompt; restart your computer.
4. Download Windows Installer from the official website of Microsoft and execute the setup program. Windows 10 0xc004c003 error will not appear again.
Perform Phone Activation
Using the slui.exe command in Run dialog launch the phone activation option. Here are the steps for you:
1. Open up Run dialog box, type “slui.exe” and click OK.
2. In the new dialog that appears, choose your country.
3. Select “Phone Activation” option, and then wait for a Microsoft representative to help you. Do not press any keys.