September 2026 KB's failing to install and rolling back

David Gamboa 0 Reputation points
2026-09-15T17:13:27.8066667+00:00

Hello,

We are facing issues when trying to deploy the latest CU. August deployed without a problem. Across multiple devices, the patch "installs" fine. The machine asks for a reboot and does the "Do not restart applying updates" Gets to 100% and then just errors out. This is the error I get: 0x800f0922 testing on other machines. It seems that it is affecting all 300+ of our computers. I have tired DISM/SFC Scannow with mounted isos as the repair files. Currently I am trying an IPU. Is anyone else dealing with this behavior or have guidance on it. No one else seems to have information, but I have had many people report the same thing when I mention it.

I have also tried increasing EFI partition space as that is what this error alludes to no luck.

Windows for business | Windows Client for IT Pros | Devices and deployment | Install Windows updates, features, or roles
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  2. Daphne Huynh (WICLOUD CORPORATION) 1,545 Reputation points Microsoft External Staff Moderator
    2026-09-16T05:33:46.98+00:00

    Welcome to Microsoft Q&A!

    Thank you for providing such a detailed description of the issue and the troubleshooting steps you have already completed.

    Based on the symptoms described, the update installs initially, requests a restart, reaches 100%, and then rolls back with error 0x800f0922. At this time, this behavior does not appear to match a broadly documented known issue with the September 2026 Windows updates.

    Error 0x800f0922 is a general servicing error that can have several possible causes, including:

    • Insufficient free space in the EFI or System Reserved partition.
    • Corruption in the Windows servicing components or pending update operations.
    • An advanced installer failure during the offline installation phase.
    • A problem involving scheduled tasks, event channels, licensing components, or another component recorded in the CBS log.

    You have already completed several of the commonly recommended troubleshooting steps, including:

    • Running DISM and SFC repairs with mounted installation media.
    • Increasing the EFI partition size.
    • Testing the update across multiple devices.
    • Attempting an in-place upgrade.

    Since these steps have not resolved the issue, the next step is to identify the exact component that is causing the rollback. On an affected device, collect and review the following logs immediately after the installation failure:

    • C:\Windows\Logs\CBS\CBS.log
    • C:\Windows\Logs\DISM\dism.log
    • Windows Update event logs
    • WindowsUpdate.log, if generated

    In the logs, search for the first occurrence of the following entries:

    • 0x800f0922
    • CBS_E_INSTALLERS_FAILED
    • Rollback
    • Advanced Installer
    • Any component-specific error recorded immediately before the rollback begins

    Please note that 0x800f0922 does not always indicate an EFI partition issue. It can also occur when a specific servicing component or advanced installer fails during the final commit phase. This may explain why the update reaches approximately 98% to 100% before being rolled back.

    Because the problem affects more than 300 devices and the standard repair steps have already been exhausted, I recommend pausing the wider deployment and opening a support case with Microsoft. When submitting the case, include:

    • CBS.log
    • DISM.log
    • WindowsUpdate.log, if available
    • The affected Windows edition, version, and OS build
    • The exact September 2026 KB number
    • A description of the deployment method
    • Information about whether the same failure occurs during a manual installation
    • A small set of representative affected devices for comparison

    Microsoft Support can perform a deeper analysis of the servicing logs and help determine which installer or Windows component is triggering the rollback.

    Reference: Error code 0x800F0922 when installing Windows updates - Windows Server | Microsoft Learn

    If you find this information helpful, please click Accept Answer. 

    Thank you for using Microsoft Q&A.

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