Cumulative Update for Windows 11, version 25H2

Hello,

It would be nice to know which update is not installing, namely the KB number in your next message.

The last 2 cumulative updates with version 25h2 from October 2025:

==► KB5066835  (14/‎10/‎2025)

==► KB5070773  (21/‎10/‎2025)

Without complicated Microsoft procedures, 2 tools are available to address the updates (tested on 2 PCs 25h2) when cumulative updates were failing with an error code.

CASE N°1

The second to last update is installed, but not the last one offered.

This won't work if it's the last update, so proceed to case N°2

Solution:

Settings --► System --► Recovery
Click on “Troubleshoot problems with Windows Update” then on “Reinstall now”
Click OK to confirm. 
Windows Update will now open and automatically begin to download and install the repair version of Windows.
Once the Windows update is complete, click Restart now to perform the repair installation. 
Once the Windows 11 repair installation is complete, log in to Windows 11.
Check Windows update.

CASE N°2

The last cumulative update from Windows Update is not installing.

Solution:

Disk cleanup (tested on a PC 25h2)

Type disk cleanup in the search box on the taskbar.
Check the boxes if present:
- Windows update cleanup
- Previous Windows installation
- Delivery optimization files
- Upgrade log files of Wind  (optional)
- Windows old (if present)

Then click on Delete files.
Duration 30 to 45 minutes.

Restart Windows Update --► Check for updates

Sometimes the last update will be right in front of you, and click on install or this last one may have started its download which will be the first step (% displayed) then move to the installation which will be the second step (% displayed), you will just need to click on Restart which will show up in Windows Update, also in the form of 2 blue circular arrows next to the time.

A CCM publication explains the procedure for W10 and is valid for W11.

==► Delete Windows Update update files

---

Hello,

Create a text file called text.txt and paste the bold text below:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\Setup\MoSetup]
"AllowUpgradesWithUnsupportedTPMOrCPU"=dword:00000001

Then go to File > Save As

In the Type field, select All Files (*.*)

Then, in the File Name field, replace .txt with .reg

Once saved, double-click the resulting .reg file and accept the modification.

There may be a chance it helps, even though personally I haven't tested this on a PC that is not compatible with Windows 11.