How to fix "We weren't able to activate Windows on this device" error?

"We weren't able to activate Windows on this device" means Windows looked for a digital licence or product key that fits this PC and its edition, and found none. The error code under the message tells you why. Read it on the Activation page, then run the Activation troubleshooter.

Facts checked on 16 October 2026. Steps written for Windows 11 (25H2 and 26H2) and Windows 10 22H2.

What "We weren't able to activate Windows on this device" means

Microsoft describes activation as pairing a product key or a digital licence with the hardware of the device. When the message appears, Windows checked both and found nothing it could pair with this PC and the edition you installed. It is a licence check, not a sign that your files or Windows itself are damaged.

The sentence is only the headline. On the Activation page, Windows is not activated comes with an error message that explains the failure, usually with a code. That code decides the fix, so write it down before you change anything.

Windows keeps working while it is not activated. Your files stay where they are, so you have time to find your key, your order email or your Microsoft account details before you try a fix.

Why Windows was not able to activate, from most to least common

Think about what happened just before the message. Each case below ties to one fix.

The code under the message narrows it down further. These are the ones we have full guides for:

How to fix "We weren't able to activate Windows on this device"

Fix 1 takes two minutes and either activates Windows or tells you which case you are in. Fix 2 is for a reinstall on a new disk, Fix 3 for a new motherboard, Fixes 4 and 5 for a product key. Fixes 6 and 7 rule out the connection and damaged files. Never use an activator tool or a key from a forum.

Fix 1. Read the error code and run the Activation troubleshooter

2 to 5 minutesNo riskEveryone who sees the message, before any other fix.

The troubleshooter is Microsoft's own check for this message. It looks again for a digital licence, finds one for another edition, and when it cannot activate it offers the hardware change path that Fix 3 uses.

1. Sign in to Windows with an administrator account and connect to the internet.
2. Open Settings > System > Activation. On Windows 10 open Settings > Update & Security > Activation.
3. Write down the edition (Home or Pro) and the error code under Windows is not activated.
4. Select Troubleshoot. Microsoft says it is offered only while Windows is not activated.
5. Wait for the check. If it reports Windows can't be activated on your device, read what it suggests.
6. A licence for another edition goes to Fix 2, the I changed hardware on this device recently link goes to Fix 3.

Fix 2. After a new SSD or a reinstall: install the same edition and sign in with your Microsoft account

10 minutes, about 1 hour if the edition must changeRead the warningThe old disk failed or was replaced, or you reinstalled Windows, and the PC was activated before with a digital licence.

Microsoft says a digital licence lets you reinstall the same edition on the same PC without a key, and Windows then activates online after setup. The licence belongs to the PC's hardware, not to the old disk, so it usually comes back when the edition and account match.

1. On the Activation page, compare the edition with the one the PC had before the disk change.
2. If the edition matches, open Settings > Accounts > Your info and check that an email address sits above Administrator. That is a Microsoft account; a local account shows no email.
3. If you use a local account, go back to the Activation page, select Add an account and sign in with the Microsoft account you used on this PC before.
4. Keep the PC online for a few minutes and open the Activation page again.
5. If the edition does not match, back up your files and reinstall the edition you own, as described below.

1. Create installation media from Microsoft's software download page and choose the edition that was activated before.
2. Start the PC from the media and install that edition.
3. When setup asks for a product key, select I don't have a product key.
4. Finish setup with the Microsoft account linked to the licence and connect to the internet.

Fix 3. After a new motherboard: choose I changed hardware on this device recently

5 minutesNo riskYou replaced the motherboard or other major parts, and your Microsoft account was linked to the licence before the change.

Windows ties the digital licence to the hardware, so a new motherboard looks like a new PC. Microsoft's hardware change path moves the licence, but only through the Microsoft account it was linked to before.

1. Sign in as an administrator and open Settings > System > Activation (Windows 10: Settings > Update & Security > Activation).
2. Select Troubleshoot and wait for Windows can't be activated on your device.
3. Select I changed hardware on this device recently, then Next.
4. Enter the Microsoft account and password linked to the licence and select Sign in.
5. In the list of devices, tick This is the device I'm using right now.
6. Select Activate.

Fix 4. Enter your product key in Settings or with slmgr

5 minutesLow riskYou bought a retail key, upgraded with a key, or the PC came with a key on a sticker or in the firmware.

Microsoft says that if you used a product key to get Windows, you need that same key again after a hardware change or reinstall. A valid key for the installed edition is exactly the licence Windows could not find.

• The confirmation email or the retailer's digital locker for a digital copy.
• The label inside the box of a retail copy.
• The packaging or the Certificate of Authenticity (COA) sticker of a PC that came with Windows.
• Your Microsoft account order history, if you bought from Microsoft online. Microsoft keeps a record of keys only for those purchases.

1. Open Settings > System > Activation (Windows 10: Settings > Update & Security > Activation).
2. Select Change product key. If User Account Control asks, select Yes.
3. Type the 25 characters and select Next, then Activate.

If Settings refuses to open the key box, do the same from Command Prompt. Type cmd in the search box, select Run as administrator next to Command Prompt, then Yes.

1. On a PC that came with Windows, read the key stored in the firmware. WMIC is deprecated, so use PowerShell:

   powershell "(Get-CimInstance -ClassName SoftwareLicensingService).OA3xOriginalProductKey"

2. Install your key, with your own characters in place of the X:

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

3. Activate it online:

   slmgr /ato

4. Check the result. This command only shows the status, it does not activate:

   slmgr /xpr

Fix 5. Activate by phone with slui 4

10 minutesNo riskYou have a valid product key, but online activation keeps failing, most often after a hardware change.

Phone activation checks the key through Microsoft's automated line instead of the online service. You read out the installation ID that Windows shows and type back the confirmation ID you are given.

1. Press Win + R, type slui 4 and press Enter.
2. Select your country or region, then Next.
3. Call a number shown on the next screen.
4. When the automated line asks, read out the installation ID shown in the window. You do not read out your product key.
5. Select Enter confirmation ID, type the ID you were given and select Activate.

Fix 6. Get the PC online and install pending updates

10 to 30 minutesNo riskThe message appeared right after setup, the troubleshooter cannot reach Microsoft, or the PC has been offline since the reinstall.

Activation with a digital licence happens online after setup, and Microsoft asks for an internet connection before every reactivation. A PC that installed offline on a new disk has simply not tried yet.

Check that the PC really reaches the internet, including through a VPN, proxy or firewall you set up: How to check your internet connection in Windows

1. Open Settings > Network & internet and check that the status says you are connected.
2. Open any website in a browser to confirm the connection really works.
3. Open Settings > Windows Update and select Check for updates.
4. Install everything offered, restart, then open the Activation page again.

A fresh installation also has many updates waiting. Install them so the system is current before you try activation again. Updates do not create a licence; they only rule out an old build. Open Settings > Windows Update (Windows 10: Settings > Update & Security > Windows Update), select Check for updates, install what is offered and restart.

Fix 7. Repair Windows system files with SFC and DISM

20 to 40 minutesNo riskEvery valid key and the troubleshooter fail, or Settings closes when you open the Activation page.

Microsoft separates activation from validation, the check that critical Windows licensing files have not been damaged, deleted or removed. SFC and DISM restore damaged system files, which rules this rare cause out.

Run both tools from an administrator Command Prompt, then restart and open the Activation page again. Step by step: Run DISM and SFC to repair Windows system files

1. Right-click Start and open Terminal (Admin) or Command Prompt (Admin).
2. Run sfc /scannow and wait until it finishes.
3. Run DISM /Online /Cleanup-Image /RestoreHealth and wait for it to finish.
4. Restart the PC and open Settings > System > Activation again.

Fix 8. No licence of your own: ask the seller or buy one

15 minutes, or the time of a purchaseNo riskYou have no key, no order and no Microsoft account link, or the PC was new, refurbished or repaired by someone else.

Microsoft says that without a digital licence or a product key you cannot activate, and that for a refurbished PC the refurbisher, not Microsoft, must supply the key.

1. Collect the order email, the receipt or the repair invoice.
2. Contact the seller from the table and give them the error code from Fix 1.
3. If you buy a licence, select Go to Store on the Activation page and follow the steps in Microsoft Store.

If Windows still says it was not able to activate

When nothing worked, the open question is which licence belongs to this hardware. Collect these facts before you contact Microsoft or the seller; they shorten the call.

A retail key or a Microsoft Store purchase goes to Microsoft customer support. Windows that came on the PC goes to the PC maker or the refurbisher. Hardware does not cause this message on its own: a faulty part shows other errors, not a missing licence.

How to avoid the activation error after the next disk or hardware change

Frequently asked questions

What do I do first when Windows says it was not able to activate?

Open the Activation page and read the edition and the error code under the message. Then select Troubleshoot. That one check either activates Windows or tells you which case you are in: a digital licence for another edition, a hardware change, or no licence at all. Only after that pick a fix from the table above. Do not reinstall Windows before you know the code, because a reinstall in the wrong edition makes it worse.

Is "We can't activate Windows on this device" the same error?

Yes, people type the same problem in both ways, and the fixes are the same. The Activation page says Windows is not activated and shows a message and a code, and the troubleshooter itself reports Windows can't be activated on your device. In every spelling the cause is a licence that does not match this PC or its edition. Follow the code under the message to the right fix.

I replaced my SSD and reinstalled Windows. Why is it not activated?

Usually because the edition or the account changed, not because of the disk. Microsoft names the motherboard as the typical change that breaks activation. With a digital licence you can reinstall the same edition without a key and Windows activates online after setup. Check that you installed Home or Pro as before, sign in with the Microsoft account you used, and stay online. If you used a key before, enter it again.

Can I reactivate Windows after a motherboard change?

Often yes, if your digital licence was linked to your Microsoft account before the change. Run Troubleshoot, choose I changed hardware on this device recently, sign in and tick This is the device I'm using right now. If you used a retail product key, enter it again, or activate by phone. Microsoft says the edition must stay the same. A licence that came preinstalled on the PC may not move to a new motherboard.

Why do I not see my PC in the troubleshooter's device list?

You are most likely signed in with another Microsoft account than the one linked to the licence. Microsoft says the troubleshooter works only with the connected account, so sign in with that one. If the licence was never linked to any account, the list stays empty. Then enter your product key (Fix 4), call phone activation (Fix 5) or ask the seller for the key (Fix 8).

Where do I find my Windows product key?

It depends on how you got Windows. A box copy has it on a label inside the box. A digital copy has it in the confirmation email or the retailer's locker. A PC that came with Windows has it on the packaging, the COA sticker or stored in the firmware, which the PowerShell line in Fix 4 reads. Microsoft keeps keys only for purchases from its own online store.

Does phone activation still work?

Yes, with a valid product key. Press Win + R, type slui 4, pick your country and call the number shown. The automated line asks for the installation ID in the window, not for your product key, and gives you a confirmation ID to type back. It is the usual way out when the key is valid but online activation refuses it after a hardware change.

Can I use a free key or an activator instead?

No. Keys posted online are not your licence, and activators and KMS scripts run against Microsoft's licence terms and run with full rights on your PC. They do not fix the missing licence behind this message. The legal ways are your own key, a digital licence in your Microsoft account, the PC maker or refurbisher, or a licence bought through Go to Store on the Activation page.

What happens if I leave Windows unactivated?

Windows keeps starting and your files stay where they are. You see the Activate Windows watermark and some personalisation settings stay locked until a licence is found. Use the time to find your key or sign in with the right Microsoft account. Once Windows is activated, the watermark goes away after a restart and nothing has to be reinstalled.