Windows update installation 25H2 failed.

Question

My computer is having a problem installing Windows 11 update 25H2. It reaches up to 90% and then starts undoing changes. It is consuming the C: disk drive memory, but the Windows installation is failed continuously.

Answer 1

Hi Mujahid Niaz,

Since the upgrade is reaching around 90% completion before rolling back, the issue is often related to a compatibility check that occurs during the final installation phase rather than the initial download.

You may want to try the following:

1, Check the EFI/System Reserved partition

• Press Win + R, type diskmgmt.msc and press Enter.
• Ensure the EFI/System Reserved partition is not completely full.

2, Disconnect unnecessary devices

• Temporarily unplug external drives, printers, docking stations, USB devices, and other peripherals.
• Restart the PC and try the upgrade again.

3, Check for disk or storage issues

• Open Command Prompt as Administrator and run: chkdsk C: /scan
• Also review Device Manager for any devices showing warning icons.

The setup logs suggested by the Volunteer Moderator will still be the useful source for identifying the exact rollback reason. If the upgrade continues to fail, sharing the relevant setup logs can help pinpoint the specific component causing the installation to revert.

Let me know if you need further assistance, feel free to ask me by clicking "Add Comment" or "Add Answer" if you cannot add comment so your response will be visible. Thanks for your effort.

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Answer 2

Step 1:

To analyze the issue and check the extended error code, please upload the following files to OneDrive or GoFile.io and post the link here:

C:\$WINDOWS.~BT\Sources\Panther\setupact.log

C:\$WINDOWS.~BT\Sources\Rollback\setupact.log

Add the files to a zip archive and upload it.

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Step 2:

Enable Memory Integrity. To do so, go to Windows Security → Device security → Core isolation details → Memory integrity. If the page lists any incompatible drivers, please post a screenshot.