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I have an issue with this update. After installing this update, my Windows became deactivated. At the Activation page in System > Activation under Settings, the Activation state becomes Not activated, with the error "Windows reported that the hardware of your device has changed. Error code: 0xC004F211". When click Troubleshoot, it says "We weren't able to activate Windows on this device." When I click "I recently changed hardware on this device" (which I clearly don't, I mean, who has the moolah to even upgrade a RAM anyway?), I signed in, then use the Authenticator notification, and key in the password, the error returned "Oops, something went wrong" and "Whatever happened, it was probably our fault. Please try again".
Funny thing is it doesn't come up with a watermark saying Activate Windows. But unfortunately, I can't personalise my desktop
Help.
Sorry, there's an error. It was supposed to be KB5079473 2026-03 Security Update, not Cumulative Update.
My key becomes invalid; there's nothing wrong with the update. Next time, please say 'your key no longer works because of abuse' from the activation screen. That save me a lot of problem and trouble. Can any of your copilot add this line to the activation screen?
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OEM keys for Microsoft Windows are meant to come with a specific PC, not be sold separately. Cheap standalone OEM keys often come from gray markets as they may work at first, but Microsoft can deactivate them later if misuse is detected.
You may need to consider contacting your reseller and if nothing happens; you may need to purchase a retail Windows license from the Microsoft Store website.
I'm not sure if you get what I'm talking about (or even understand my situation), but it's okay. I found out that my key has been marked 'abused' by Microsoft. It would be better if they just say, 'we can't activate Windows with this key because of possible abuse' or 'your key no longer valid because of suspicious abuse' rather than 'oops, something wrong with our side, please try again later'. That should save me all the confusion.
Please try to return to the login screen
While holding the Left Shift key, click the Power icon > Restart
This will bring you to Windows Recovery Environment
Select Troubleshoot > Advanced Options > Uninstall Updates
Uninstall latest quality update
If this doesn't work, Select Troubleshoot > Advanced Options > System Restore
Select the restore point at an earlier date where everything is still working.
Click Next then Finish
Appreciate your answers. I'll try this. It'll take lots of times. There goes my weekend.
Nope, not working. Recovery options are not available, no backup or restore point.
But, yeah, I have to check my reseller about that. But strange is how Microsoft just deactivate my Windows. I bought a license with my new custom-built PC back then, and the shop install Windows for me, gave me the envelope containing the COA sticker, and ask me to activate the Windows. I'm the one who tore the envelope as the envelope was sealed.
Hi, good day!
Did your device come with Windows preinstalled or did you purchase it separately?
Open and run Command Prompt as administrator
Copy and paste the command below then press Enter
slmgr /dlv
Please take a screenshot of the resulting window and post it in your next response.
I look forward to receiving your update and I'm willing to collaborate with you till we resolve the issue. Do keep me informed by clicking "Add comment" below.
Hi, I purchase it separately. It was a custom build machine.
Here's what I got from the command prompt slmgr /dlv.
I did try to input my key again. No luck. It is a Windows 10 key. I wonder if it is incompatible with Windows 11.
Where did you buy the Windows license key? Did you buy it from a third-party website?
Unfortunately, OEM DM license usually can’t be used on a custom-built PC. It’s embedded in the original computer’s motherboard and is tied to that specific device, so it won’t transfer to different hardware. It’s better to use a Retail license (transferable) for custom-built PC which you can purchase on the Microsoft Store website.
It's been a long time; I think I bought it back in 2019 (RM500+) when I build this PC. I have the OEM Disc and the envelope. Activated it without issue, until the recent Windows update.
I did reinstall once back at year 2021, At that time it was still Windows 10, and it immediately activate with a digital license.
So, it stayed in my system, even being upgraded to Windows 11 forcefully, and no issue. Just that when my system installed 2026-03 security update, it works for a while and then Windows goes coo-coo.
Error 0xC004F211 means Windows thinks significant hardware has changed and can no longer match the existing digital license to the device.
Since the Activation Troubleshooter path is failing with “Oops, something went wrong,” and normal self-service reactivation is not working, the remaining supported option is to contact Microsoft support so the activation can be corrected on the backend.
Steps to try first (if not already done):
If Windows originally came preinstalled (OEM) and the motherboard was ever replaced in the past, support may also confirm whether a new license is required, but for a case triggered only by an update, support reactivation is the expected resolution.
References: