Windows activation error 0xC004C003: Key used on multiple devices
Updated
Cleared for publishing after the automated checks on .
What the code means
The product key you entered isn't valid. A key is meant for one user on one device; a key that was used, or tried, on more than one device is marked as not valid. (Get help with Windows activation errors)
Volume activation (IT): The activation server determined the specified product key is blocked. (Troubleshoot Windows activation error codes)
Code facts for 0xC004C003
| Code as Windows shows it | 0xC004C003 |
|---|---|
| Type | Activation error code |
| Hexadecimal, 8 digits | 0xC004C003 |
| Decimal (unsigned) | 3221536771 |
| Decimal (signed 32-bit) | -1073430525 |
| Group | Activation errors |
Read with care
- Not a standard HRESULT (R bit set without the N bit, MS-ERREF 2.1). Microsoft lists it as a Windows activation (Software Protection) code; do not split it into facility and error number. ([MS-ERREF]: HRESULT, Troubleshoot Windows activation error codes)
Code facts: Get help with Windows activation errors (Microsoft Support), checked Nov 14, 2026. Summary in our own words; Microsoft's page has the full steps.
Code facts: Troubleshoot Windows activation error codes (Microsoft Learn, CC BY 4.0), checked Nov 14, 2026.
Where this error shows up
This code shows up when Windows tries to activate or when the product key is checked.
Applies to
Windows 11 and Windows 10 (page has a section for each). Windows 10 support ended 14 Oct 2025 per page.
Try these first
These steps carry no risk flag in the data. They keep the order of the full list below, which is not reordered. A step without a flag is not a promise that it is safe for your computer.
4 steps to try, in order
Steps are grouped by the Microsoft page they come from. The page lists only what those pages give; other causes of 0xC004C003 are not covered.
If this page and Microsoft's page differ, follow Microsoft's page.
From: Get help with Windows activation errors
Source: Get help with Windows activation errors (Microsoft Support), checked Nov 14, 2026. Summary in our own words; Microsoft's page has the full steps.
Steps follow the Windows 11 tab of Microsoft's activation help page; its Windows 10 tab has its own version of this row (Windows 10 support ended on October 14, 2025).
Get a key that belongs to this device
You need a different Windows key that is unique to this device.
Bought from a reseller and expected a valid key? Contact the reseller. Windows came preinstalled and the error appeared the first time you turned the device on? Contact the device maker.
Other things to try
Run the Activation troubleshooter: Start > Settings > System > Activation > Troubleshoot.
Look for a paper copy of your 25-character product key and enter it.
After a repair at an independent shop, ask the shop whether the work means you need a fresh Windows 11 license. A brand-new device that has never been activated is a matter for its maker.
From: Troubleshoot Windows activation error codes
Source: Troubleshoot Windows activation error codes (Microsoft Learn), checked Nov 14, 2026. © Microsoft, licensed under CC BY 4.0. Steps shortened and reworded by PC Driver Update.
Microsoft's volume activation (MAK/KMS) error page, written for technical support agents and IT professionals.
Get a new MAK
Written for IT administrators.
The MAK is blocked on the activation server. Contact the Microsoft Licensing Activation Centers to obtain a new MAK, then try installing and activating Windows again.
From: Error 0xC004C003 "product key is blocked" when you use MAK to activate Windows
Source: Error 0xC004C003 "product key is blocked" when you use MAK to activate Windows (Microsoft Learn), checked Nov 14, 2026. © Microsoft, licensed under CC BY 4.0. Steps shortened and reworded by PC Driver Update.
Microsoft's page for 0xC004C003 with a Multiple Activation Key (MAK); written for IT professionals, applies to Windows client, Windows Server and Azure VMs. It expects you to know the slmgr script.
Get and install a new MAK
Written for IT administrators.
The MAK configured on the client is blocked on the activation server (for example reported as stolen or misused, an expired trial or evaluation key, a key that doesn't match the installed edition, or a key from an on-premises machine moved to Azure).
Contact the Microsoft Licensing Activation Centers to obtain a new MAK. Install it from an administrative Command Prompt: slmgr -/ipk <xxxxx-xxxxx-xxxxx-xxxxx-xxxxx>
Try to activate again: cscript c:\windows\system32\slmgr.vbs /ato. If activation fails, contact Microsoft Support (Azure VMs: the page's Step 2 switches the VM to Azure KMS).
Stop and get help
If these steps do not fix the problem, or you are not sure about a step, stop and get help from Microsoft Support or from the maker of your PC. Stop at once if the data on this computer is at risk: back up your files first, or ask a professional before you go on.
Dates and review
| Automated checks | first check: ; second check: ; third check: ; fourth check: |
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| Microsoft pages read |
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| Review status | Cleared for publishing after the automated checks on . |