How to fix Windows activation error 0xC004C020?

Error 0xC004C020 means the key in Windows is a Multiple Activation Key (MAK), a volume key bought by an organisation, and it has been used on more devices than its limit allows. Nothing on your PC is broken. Check which key Windows holds first, then replace it with your own licence or ask the key's owner.

Facts checked on 15 October 2026. Steps written for Windows 11 (25H2 and 26H2) and Windows 10 22H2.

What Windows activation error 0xC004C020 means

Microsoft's activation troubleshooting page for IT staff names the error "0xC004C020 The activation server reported that the Multiple Activation Key has exceeded its limit". It adds that a MAK can be activated only a limited number of times, by design. Once that number is used up, the server refuses every new activation with the same key.

Microsoft's page for home users says the same in plain words. The error occurs when a Volume License was used on more devices than the Microsoft Software License Terms allow. A Volume License is one an organisation bought from Microsoft to install Windows on many devices. Its advice is to use a different product key, and to contact your organisation's support person.

Why error 0xC004C020 appears, from most to least common

The code is about the key, not the PC. So the question that decides the fix is how a volume key got into your Windows. Find your row and go to its fix.

The reader's question above is the third row. A licence bought from Microsoft's store is never a MAK, so a clean install that ends in 0xC004C020 means a volume key was entered instead of that licence. Fix 1 shows it, and Fix 2 or Fix 3 puts the bought licence back.

How to fix Windows activation error 0xC004C020

Fix 1 tells you which kind of key Windows holds, in one command. Fixes 2 and 3 are for people who bought Windows themselves. Fixes 4 and 5 are for work, school and company PCs. Fix 6 is for a key bought on its own, and Fix 7 is for a genuine purchase that still fails. No repair tool or update raises a MAK limit, so they are left out.

Fix 1. Check which licence key Windows holds with slmgr /dli

2 minutesNo riskEveryone, before anything else. It takes one minute and tells you which fix is yours.

0xC004C020 is returned only for a Multiple Activation Key, so the licence channel tells you whether Windows really holds a volume key and whose it may be. The last five characters let you compare it with the key you bought.

1. Open Start, type cmd, right-click Command Prompt and select Run as administrator.
2. Select Yes in the User Account Control window.
3. Type slmgr /dli and press Enter.
4. Wait a few seconds for the Windows Script Host box and read the Description line and the Partial Product Key.
5. Select OK to close the box.

Write down the five characters after Partial Product Key. If they do not match the end of the key on your order email or box card, the key in Windows is not yours.

Fix 2. Replace the volume key with your own product key

3 to 5 minutesNo riskYou have a genuine key: a retail box card, a Microsoft Store confirmation email, or a COA sticker on a PC that came with Windows.

Microsoft's advice for this code is to use a different product key. A new key overwrites the MAK, and a retail or OEM key is counted against your own licence, not the organisation's used-up limit.

1. Open Settings > System > Activation (Windows 10: Settings > Update & Security > Activation).
2. Select Change product key. Windows may ask for an administrator password.
3. Type the 25-character key and select Next, then Activate.
4. Wait for the page to update, then run slmgr /dli again: the channel should no longer say VOLUME_MAK.

To do the same from Command Prompt, which gives a clearer message when it fails, run Command Prompt as administrator and use these two commands.

Install your key and activate online

slmgr /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
slmgr /ato

Fix 3. Get your digital licence back with the Activation troubleshooter

5 to 10 minutesNo riskYou bought Windows from the Microsoft Store, upgraded for free, or the PC was activated before the clean install, and you have no key to type.

A digital licence is linked to the PC's hardware and often to your Microsoft account, but Windows uses it only when no other key is installed. While the MAK is in place, Windows keeps trying that key. The troubleshooter looks up the licence for this device.

1. Check that the PC is online. Activation needs a working connection: How to check your internet connection in Windows
2. Open Settings > System > Activation (Windows 10: Settings > Update & Security > Activation).
3. Select Troubleshoot and wait for the scan.
4. If it offers to sign in, use the Microsoft account you bought Windows with or used on this PC before.
5. If the troubleshooter finds the licence, follow its prompt to activate.

If the motherboard was replaced since the last activation, this is a different problem. Our guide to Windows activation error 0xC004F211 covers moving a licence after a hardware change.

Fix 4. Work, school or second-hand PC: ask the organisation's IT team

5 minutes, plus the IT team's replyNo riskThe PC belongs to an employer or school, was set up by an IT team, or was bought second-hand from a company or refurbisher.

The MAK belongs to the organisation that bought the volume licence. Microsoft's own advice for 0xC004C020 is to contact your organisation's support person, because only the licence owner can issue another key or ask Microsoft for more activations.

1. Run slmgr /dli (Fix 1) and note the Description line and the Partial Product Key.
2. Take a screenshot of the Activation page with the code 0xC004C020.
3. Send both to your IT team or helpdesk, with the PC name from Settings > System > About.
4. Wait for their instructions. They may give you a new key, ask you to connect to the company network, or add activations to the MAK.

Fix 5. IT admin: request more MAK activations from Microsoft

15 minutes, plus Microsoft's replyNo riskYou manage the organisation's volume licence and company PCs report 0xC004C020.

Microsoft's IT troubleshooting page gives exactly this fix: by design a MAK has a limited number of activations, and if you need more you request them from the Microsoft Licensing Activation Centers.

1. Collect the MAK's last five characters from slmgr /dli on an affected PC, and your volume licence agreement details.
2. Count how many devices really need activation, including PCs that were reinstalled or replaced.
3. Open Microsoft's Licensing Activation Centers page, which Microsoft links from its activation error page, and find the contact for your region.
4. Request more activations for the MAK and give the agreement details.
5. When Microsoft confirms the increase, run slmgr /ato on each affected PC.

Activate again after the limit is raised

slmgr /ato

Fix 6. Ask the seller of a separately bought key for a refund, then get a genuine licence

15 minutes, plus the seller's replyNo riskYou bought the key on its own from a marketplace, an auction or a cheap key website, and Fix 1 shows VOLUME_MAK.

A MAK is meant for an organisation's own devices under its volume licence agreement. A key sold to you on its own that returns this code is a volume key whose limit is used up, and nothing on your PC can raise that limit.

1. Take a screenshot of the error with the code 0xC004C020 visible, and of the slmgr /dli result showing VOLUME_MAK.
2. Find your order: the seller's email, the marketplace order page and the key.
3. Write to the seller and ask for a refund, quoting Microsoft's meaning: the key is a volume licence used on more devices than allowed.
4. If the seller does not answer, open a dispute with the marketplace or payment provider and attach the screenshots.
5. Buy a genuine licence: open Settings > System > Activation and select Go to Microsoft Store, or buy a boxed key card from a retailer and enter it with Fix 2.

Fix 7. Contact Microsoft support with proof of a genuine purchase

15 to 30 minutesNo riskYou bought Windows from Microsoft or an authorised retailer, Fix 1 shows your own key or digital licence should apply, and Fixes 2 and 3 did not activate.

Microsoft's error page sends codes it cannot solve on the page to customer support. Support can look up a purchase and the state of a key, which nothing on the PC can do.

1. Collect the proof: the order number or confirmation email, the account used to buy, and a photo of any key card.
2. Take a screenshot of the Activation page and of the slmgr /dli result.
3. Check the PC's date, time and time zone before you contact them: How to fix the date and time in Windows
4. Open support.microsoft.com/contactus in a browser and choose Windows activation.
5. Give support all the facts in one message, including that the error is 0xC004C020 and the channel slmgr /dli showed.

If error 0xC004C020 is still there

When none of the fixes worked, the question is not technical any more. It is whose key is in Windows and whether its owner can add activations. Collect these facts before you ask your IT team, the seller or Microsoft.

How to avoid error 0xC004C020 next time

On a home PC, the error starts with a volume key that should never have been there. Keep your own licence in Windows and the code does not come back.

Frequently asked questions

What does error code 0xC004C020 mean?

It means the activation server refused a Multiple Activation Key because its limit is used up. Microsoft's wording is "The activation server reported that the Multiple Activation Key has exceeded its limit." A MAK is a volume key an organisation buys to activate a set number of devices. Nothing on your PC is damaged, and no repair tool changes the count, which is kept on Microsoft's server.

How do I fix 0xC004C020 on Windows 11?

First run slmgr /dli in Command Prompt as administrator to see the key's channel. If it says VOLUME_MAK and you own a retail or Store licence, replace the key under Settings > System > Activation > Change product key, or run the Activation troubleshooter to restore your digital licence. On a work or school PC, contact the IT team. The steps are Fix 1 to Fix 4 above.

Why do I get 0xC004C020 after a clean install with a licence from the Microsoft Store?

A Microsoft Store licence is a retail digital licence, not a volume key, so it never produces this code itself. After a clean install the error means a volume key was entered, often from a company install image or a key typed in during setup. Run slmgr /dli, then use Change product key with your own key, or the Activation troubleshooter with your Microsoft account. Check that the edition matches the one you bought.

What is a Multiple Activation Key (MAK)?

A MAK is a volume licence key that Microsoft sells to organisations so they can activate Windows on many devices with one key. Microsoft says each MAK can be activated only a limited number of times, by design. Each device activates once with Microsoft's servers, and the count goes down. When it reaches zero, new activations fail with 0xC004C020 until the organisation asks Microsoft for more.

I bought a cheap Windows key online and got 0xC004C020. Is it fake?

It is not a retail key. The code is returned only for a Multiple Activation Key, which is meant for an organisation's own devices under its volume licence. A key sold to you on its own that shows this error is a volume key whose limit is used up. Ask the seller for a refund, as in Fix 6, and buy a licence from the Microsoft Store or a retailer.

Can Microsoft raise the activation limit of a MAK?

Yes, for the organisation that owns the licence. Microsoft's IT troubleshooting page says you can request more activations from the Microsoft Licensing Activation Centers. That request comes from the organisation's licensing contact with its agreement details. A home user who received a MAK from a third party cannot make that request, because the key is not theirs.

Will phone activation with SLUI 4 fix 0xC004C020?

We could not confirm that it does, and Microsoft does not list it for this code. Microsoft recommends phone activation with SLUI 04 for errors where the PC cannot reach the activation servers, such as 0xC004FC03. For 0xC004C020, its advice is a different product key or more activations from the Licensing Activation Centers. Older guides suggested the phone route, so this page no longer does.

Is 0xC004C020 the same as 0xC004C008 or 0xC004C003?

They are related volume licence errors with different meanings. Microsoft says 0xC004C008 appears when a KMS host key has exceeded its activation limit, and 0xC004C003 means the MAK is blocked on the activation server. 0xC004C020 means a MAK has exceeded its own limit. All three point to the key, not the PC, and all three are solved with a new key or more activations.

The message says the product key "has exceeded its unlock limit". Is that this error?

Users also search for that wording, but we could not find it in Microsoft's documentation for 0xC004C020. Microsoft's wording is that the Multiple Activation Key has exceeded its limit. If your message shows the code 0xC004C020, the meaning and fixes on this page apply. If it shows another code, look up that code, because the fix depends on it.

What about "printer not activated error code 20" or "the software licence checkout failed error 20"?

Those are different errors from other software, not Windows activation error 0xC004C020. This page is only about the Windows volume licence code. A printer that is not activated and a software licence checkout failure come from the printer driver or from the licensing system of another program. Search for the exact message together with the program's name, or ask its maker's support.