Latest Windows Update?

Remove the repeatedly failing KB5126657 through Windows Recovery Environment before allowing another installation attempt, because seven failed cycles warrant rollback rather than another forced restart.

Remove the failed update

Uninstalling a security update temporarily removes its protections, but it is safer than repeatedly interrupting an installation at 99%.

If Windows still reaches the desktop:

1. Open Start > Settings > Update & Security > Windows Update.
2. Select View update history > Uninstall updates.
3. Select KB5126657, if listed, and choose Uninstall.
4. Restart normally and confirm Windows reaches the sign-in screen. Some updates cannot be uninstalled from Settings.^1^

If Windows becomes stuck again or cannot reach the desktop:

1. Enter the Windows Recovery Environment using the repair tool or recovery screen that has been restoring the PC.
2. Select Troubleshoot > Advanced options > Uninstall Updates.
3. Select Uninstall latest quality update. KB5126657 is a cumulative quality/security update.
4. Restart and confirm Windows loads normally.^1^

If Windows Recovery reports that no quality update can be removed, the failed installation has probably already been rolled back; continue with the checks below rather than forcing another repair cycle.

Before attempting it again

Microsoft does not currently document a KB5126657 issue matching a restart frozen at 99%. Its documented known issue concerns certain USB Audio Class 1.0 devices, not installation progress.^2^ The Windows 10 22H2 release-health page likewise does not list this symptom.^3^

After Windows is stable:

1. Back up important files.
2. Disconnect unnecessary USB drives, docks, printers, and other external hardware.
3. Ensure drive C: has at least 20 GB free, because this is 64-bit Windows 10.
4. Run the Windows 10 troubleshooter:
   • Start > Settings > Update & Security > Troubleshoot > Additional troubleshooters
   • Select Windows Update > Run the troubleshooter.
5. Clear the downloaded update files:
   • Press Win+R, enter services.msc, and press Enter.
   • Right-click Windows Update and select Stop.
   • Open C:\Windows\SoftwareDistribution.
   • Delete the contents of that folder.
   • Return to Services, right-click Windows Update, and select Start.
6. Restart once, then check Windows Update again. Microsoft recommends the troubleshooter when an installation remains between 51% and 99%, and documents the cache-reset procedure for damaged update files.^4^

Windows 10 servicing status

Windows 10 reached end of support on October 14, 2025. KB5126657 applies to Windows 10 22H2 devices receiving Extended Security Updates (ESU).^2^ ^3^

If the same 99% failure occurs after the cleanup, do not repeat the repair cycle. Open the Get Help app and contact Microsoft Support with:

• Update: KB5126657
• Windows version: 22H2 x64
• Number of failures: seven
• Whether rollback succeeded
• Any error code shown under Settings > Update & Security > Windows Update > View update history

Microsoft identifies Get Help or Microsoft Support as the direct support route for home PCs.^3^

References

1. [Windows 10](https://support.microsoft.com/windows/deployment/updates-lifecycle/how-to-uninstall-a-windows-update#uninstall-an-update-from-windows-re)
2. October 13, 2026—KB5126657 (OS Builds 19045.7807 and 19044.7807 ...
3. Windows 10, version 22H2 known issues and notifications
4. [Windows 10](https://support.microsoft.com/windows/deployment/updates-lifecycle/troubleshoot-problems-updating-windows#most-common-windows-update-problems)