Why does my PC say "Activate Windows", and what should I do about it?
The watermark in the corner and the greyed-out personalisation settings. What actually stops working, why it usually appears after a hardware change or a reinstall, and how to get it back without buying anything.
- Difficulty
- beginner
- Time
- 25 min
- Read
- 5 min
- Safety
- caution
Short answer
Activation is a licence check, not a subscription, and it usually breaks for one of three reasons: a hardware change the licence no longer recognises, a reinstall that could not find the key, or a key that was never valid. Run the built-in activation troubleshooter first — if the machine came with Windows and you have signed in with the Microsoft account it was linked to, that reconnects the licence in a couple of minutes at no cost.
An unactivated Windows machine is not crippled. It updates, it runs everything, it is not on a countdown. What you lose is personalisation — wallpaper, colours, themes and lock screen settings go grey — and you get a translucent watermark over the bottom-right corner that appears in screenshots and screen shares. That is the whole penalty. Knowing this matters, because the gap between the alarm the watermark creates and the actual consequence is exactly the gap that fake activation tools and scam pop-ups exploit.
Safety
Step by step
- Work out when it started.Immediately after replacing a motherboard or a drive, after a reinstall, after a Windows upgrade, or apparently out of nowhere on a machine that has been fine for years. Each points at a different cause and the last one usually means a temporary Microsoft server problem, which resolves itself.
- Run the built-in activation troubleshooter.Settings, System, Activation. If the machine is not activated there is a Troubleshoot option. It handles the standard case — a licence linked to your Microsoft account and hardware that has changed — and it is the officially supported route for a motherboard replacement.
- Sign in with the right Microsoft account.Digital licences are attached to a Microsoft account. If you set the machine up with a local account, or a different email from the one the licence was linked to, the troubleshooter has nothing to match. Signing in with the correct account is often the entire fix.
- Check whether the licence is in the firmware.Machines sold with Windows preinstalled since roughly Windows 8 carry the key in the motherboard firmware. A clean install of the same edition finds it automatically. If it did not, you may have installed the wrong edition — Pro media on a machine licensed for Home, for example.
- Confirm you have the edition you are licensed for.Settings, System, About shows the edition. Installing Pro on a Home licence produces exactly this symptom. Reinstalling the correct edition resolves it, and it is a far better answer than buying a Pro licence you do not need.
- Wait out a server-side blip.Activation is an online check and Microsoft's servers occasionally fail it in waves — this has happened publicly more than once. If nothing about your machine has changed and the watermark appeared on its own, give it a day or two before spending money.
- Buy properly if you genuinely need a licence.A self-built machine, or one that never had Windows, needs a licence bought from Microsoft or a mainstream retailer. Expect to pay a normal price. A key at a tenth of the price is a resold volume licence and Microsoft can and does deactivate them.
- Never run an activation cracker.Tools that promise to activate Windows for free are among the most consistently malware-laden downloads there are, and the machines they target are already unprotected. The watermark is cosmetic. Living with it is strictly safer than removing it that way.
Common mistakes
- Buying a five-pound key from a marketplace — Those are volume or education licences being resold outside their terms. They frequently deactivate weeks or months later, and there is no recourse. You end up buying twice.
- Treating the watermark as urgent — Nothing stops working and there is no deadline. That urgency is manufactured by the sites selling keys and the pop-ups selling scams. Taking a week to sort it out properly costs nothing.
- Reinstalling Windows to fix activation — It rarely helps and usually makes it worse, because a reinstall of the wrong edition is one of the causes. Check the edition and the account first.
If it doesn't work
Appeared after replacing the motherboard
Cause: The digital licence is tied to the old hardware — Fix: This is exactly what the activation troubleshooter's "I changed hardware on this device recently" path is for. It needs the machine signed into the Microsoft account the licence was linked to.
Appeared after a clean install
Cause: Wrong edition, or the key not read from firmware — Fix: Check the edition against what the machine was sold with. Reinstalling the matching edition usually activates silently within a few minutes of going online.
Says the key is being used on another device
Cause: A resold or transferred licence — Fix: A retail licence moves between machines; an OEM licence does not. If the key came from a marketplace listing, this is the expected outcome and there is usually no remedy.
A window insists you call a support number
Cause: A tech support scam, not Microsoft — Fix: Close it. Microsoft does not put phone numbers in error messages. The catalogue's guide on tech support scams covers what to do if you have already called.
Activated yesterday, unactivated today, nothing changed
Cause: A server-side activation problem — Fix: Wait. These have happened at scale and been fixed by Microsoft without any action from users.
Personalisation settings are greyed out and nothing else is wrong
Cause: That is the normal unactivated state — Fix: Wallpaper can still be set by right-clicking an image and choosing Set as desktop background, which sidesteps the greyed-out panel.
Questions people ask
What actually stops working if I ignore it?
Personalisation settings are locked and a watermark sits over the bottom-right corner. Updates, security updates and every application continue to work normally, and there is no expiry. It is a nag, not a countdown.
Do I have to pay if my computer came with Windows?
No. That machine is licensed, and the licence usually lives in the motherboard firmware or in the Microsoft account it was linked to. Almost every activation problem on a preinstalled machine is a matching problem, not a licensing one.
Can I move my Windows licence to a new computer?
A retail licence — one you bought separately in a box or as a download — can be moved, after removing it from the old machine. An OEM licence, which is what comes preinstalled, is tied to the original motherboard for its life and cannot be transferred.
Does Windows 11 Home really need a Microsoft account?
Setup pushes very hard towards one, and there are practical reasons to use one — a digital licence attached to an account is what makes hardware changes recoverable, and it is where a BitLocker recovery key is stored. That is the honest argument for it, separately from the fact that Microsoft wants it.