Hi theodore marinos
I'm sorry to give you bad news, but you cannot install Windows 11 with a Windows 8 license anymore.
You'll need to buy a new license.
Can't activate Windows 11 with legit Windows 10 licence
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theodore marinos
20
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Originally, years ago, I had a genuine Windows 8 license on a custom-built PC. When Microsoft offered the free upgrade to Windows 10 for genuine Windows 7/8 users, I used that offer, and my system upgraded to Windows 10 Professional, tied to my Microsoft account.
Since then, I've gradually replaced almost every piece of hardware — new CPU, new motherboard, new graphics card, new RAM, new power supply — over several years, but kept using the same Windows 10 Pro installation and the same Microsoft account the whole time.
A few days ago, I did a fresh, clean install of Windows 11 Professional on a brand new SSD, using that same Microsoft account.
Windows 11 installed correctly as Professional, but won't activate — I get error 0x803F7001. I believe this is because the hardware has changed enough over the years that your system isn't recognizing this as the same continuous license — it might even be showing two separate device entries under my account, one old and one current.
Windows for home | Windows 11 | Licensing and activation
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Spigolo
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theodore marinos 20 Reputation points
2026-06-26T11:30:36.06+00:00 Perhaps I phrased it wrong. My Microsoft account is linked to a genuine Windows 10 Pro account
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Spigolo 136.2K Reputation points Volunteer Moderator
2026-06-26T11:54:31.2466667+00:00 I understand, but that license comes from an 8. You can't upgrade it anymore.
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Neil D 34,305 Reputation points Volunteer Moderator2026-06-26T11:58:18.7533333+00:00 The previous answer is correct. Microsoft have now blocked a Windows 10 licence upgraded from Windows 7/8 to activate Windows 11.
Only an original Windows 10 licence can be used to activate Windows 11.
In many ways you have been lucky in the past to change hardware and be able to continue to activate Windows 10. The free upgrade from Windows 7/8 was for the life of the device and when you change major hardware it is a new device. This is also applied vigorously as Microsoft have said they have closed the loophole that allowed users to continue to use the free upgrade outside of the free upgrade period, 2015 - 2016.