Microsoft confirmed EFI free space issue with installing May updates for Windows 11 24H2 / 25H2

Microsoft has confirmed that some devices running Windows 11 versions 24H2 and 25H2 may experience an issue installing cumulative update KB5089549, released May 12, 2026. The failure reportedly occurs approximately 35% of the way through the update, during the reboot to apply the changes. The error code is 0x800f0922.

The problem occurs due to insufficient free space on the EFI System Partition (ESP). It most often occurs on devices with 10 MB or less of free space on the EFI partition. When an error occurs, the operating system aborts the process, rolls back changes, and displays the familiar message: "Something went wrong. Reverting changes."

On affected devices, the log file along the path C:\Windows\Logs\CBS\CBS.logmay contain entries that directly indicate a lack of space, such as:

• SpaceCheck: Insufficient free space
• ServicingBootFiles failed. Error = 0x70
• SpaceCheck: used by third-party/OEM files outside of Microsoft boot directories

Microsoft claims to have partially addressed the issue using Known Issue Rollback (KIR) technology. However, this only affects end-user devices and unmanaged corporate devices. In most cases, simply restarting the computer and checking for updates again is sufficient.

On managed corporate devices, administrators will have to manually apply a workaround through Group Policy.

How to fix error 0x800f0922 on Windows 11

If you're still encountering error 0x800f0922, you can manually fix the issue by following these instructions from Microsoft:

1. Open the Start menu.
2. Type "Command Prompt", right-click on the search result and select "Run as administrator".
3. In the window that opens, enter the following command and press Enter:
   reg add "HKLM\SYSTEM\CurrentControlSet\Control\Bfsvc" /v EspPaddingPercent /t REG_DWORD /d 0 /f
4. Restart your computer.
5. Open Settings.
6. Go to the Windows Update section.
7. Click the "Check for Updates" button