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upgrade to 25H2 from 21H2

Imangali 10A 20 Reputation points
2025-10-13T07:42:20.2333333+00:00

I just bought a brand new high end pc, but it came with 21h2, when i try to upgrade to 25h2 using the windows 11 installation assistant from microsoft website, the first step of 3, which is downloads to 100% without problem and so is the 2nd step but on the 3rd step, which is installing, my pc restarts at 88% percent at the installing. ive seen some reddit posts saying that it should restart and complete it itself, however it doesnt open the installation assistant app by itself after restarting, i wonder what to do about it, and plus i never got offered any update or whatever from my pc's default windows update settings screen, it just says that its missing security updates, thats why im trying to upgrade from 21h2 to 25h2 to fix the problem and recieve the important updates on time

Windows for home | Windows 11 | Install and upgrade
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Answer accepted by question author

DaveM121 882.8K Reputation points Independent Advisor
2025-10-13T08:14:21.65+00:00

The most successful method to install version 25H2 is to use the Windows 11 ISO, which is the bottom (3rd) link on the Microsoft web page.

Please ensure you download the ISO in the same language as you use for the Windows UI, follow the steps, this is then not like re-installing Windows, it is just like an update and your personal files, settings and installed software will not be affected.

Click this link:

https://www.microsoft.com/software-download/windows11

to download the Windows 11 ISO

When the ISO file completes downloading

Disconnect from the Internet

Disconnect all external devices with the exception of a mouse or keyboard.

Temporarily disable any 3rd party Anti-virus you may have installed

Then, in Windows File Explorer, double click the ISO and then run Setup.exe and select the Install option.

Very Important - ensure you select the option to keep your files and apps.

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