Assistance Required - Failure to Deploy KB5089549 on Windows 11 24H2 Systems

For Windows 11 24H2 devices, KB5089549 is a known update that can fail under specific conditions, especially on some devices and in certain deployment scenarios.

From the available information, there are two main, documented problem patterns related to KB5089549 and large monthly security updates on Windows 11 24H2/25H2:

1. Failure with error 0x800f0922 due to limited EFI System Partition (ESP) space
   • After installing the May 2026 security update KB5089549 (OS Build 26100.8457), some devices fail to complete installation with error 0x800f0922.
   • This specifically affects devices with limited free space on the EFI System Partition (ESP), especially when 10 MB or less is available.
   • The update progresses through initial phases, then fails around 35–36% during reboot and rolls back with messages like “Something didn’t go as planned. Undoing changes.”
   • CBS logs on affected devices show entries such as:
     • SpaceCheck: Insufficient free space
     • ServicingBootFiles failed.Error = 0x70
     • SpaceCheck: <value> used by third-party/OEM files outside of Microsoft boot directories
2. General reliability issues with KB5089549 that have since been fixed
   • The issue with KB5089549 failing to install on some Windows 11 24H2/25H2 devices has been officially resolved by a later update KB5089573 (released May 26, 2026) and later cumulative updates.
   • The recommendation is to ensure affected devices receive KB5089573 or any later cumulative update, which includes fixes for this issue.

Given the scenario (Ivanti-based deployment, large cumulative updates, some devices succeed while others fail), the most likely root causes based on the documented behavior are:

• Insufficient ESP free space on a subset of devices (leading to 0x800f0922 and rollback during reboot), and/or
• Devices not yet updated to a build that includes KB5089573 or later, so they still hit the original KB5089549 issue.

Recommended troubleshooting and remediation steps

1. Check whether affected devices have received KB5089573 or later
   • On a sample of failing Windows 11 24H2 endpoints, verify if KB5089573 (or any later cumulative update that supersedes it) is installed.
   • If not, prioritize deployment of KB5089573 or a newer cumulative update to those devices. Once installed, retry KB5089549 or allow the newer cumulative update to supersede it.
2. Verify if failures match the known 0x800f0922 / ESP space issue
   • On failing endpoints, review C:\Windows\Logs\CBS\CBS.log for entries like:
     • SpaceCheck: Insufficient free space
     • ServicingBootFiles failed.Error = 0x70
     • SpaceCheck: <value> used by third-party/OEM files outside of Microsoft boot directories
   • If these entries are present, the failures are consistent with the EFI System Partition free-space issue.
3. If still on pre–May 26, 2026 builds, apply the documented workaround For devices that cannot yet install KB5089573 or later, the following workarounds are documented: Option A – Adjust ESP padding via registry

   Warning: Editing the registry incorrectly can cause system issues. Ensure registry backups and change control are in place.

   On affected devices:
   1. Open Command Prompt as Administrator.
   2. Run:

            reg add "HKLM\SYSTEM\CurrentControlSet\Control\Bfsvc" /v EspPaddingPercent /t REG_DWORD /d 0 /f
      

   3. Restart the device.
   4. Retry installing KB5089549 (either via Ivanti or Windows Update).
   Option B – Use Known Issue Rollback (KIR) for managed environments
   • This issue is mitigated using Known Issue Rollback (KIR).
   • For enterprise-managed devices, IT can apply the KIR via Group Policy:
     • Download and deploy the KIR policy package for Windows 11 24H2/25H2:
       • KB5089549 260514_06221 Known Issue Rollback (MSI).
     • Import and configure the Group Policy under:
       • Computer Configuration > Administrative Templates > <Group Policy name from the KIR package>
   • After applying the KIR and updating Group Policy on clients, restart the devices and retry the deployment.
4. Use direct/manual installation as a validation step
   • On a subset of failing endpoints, manually install KB5089549 (matching architecture and version) to validate whether the issue is specific to Ivanti deployment or to the OS/update state.
   • If manual installation succeeds after applying the above workarounds or after installing KB5089573, then Ivanti can continue to deploy the same update, relying on the OS-side fix.
5. Ongoing mitigation for future large security updates
   • Since the issue is tied to ESP space and was fixed in later cumulative updates, ensure:
     • All Windows 11 24H2 endpoints are kept current with KB5089573 or later.
     • For devices with custom OEM or third-party content in the ESP, coordinate with the OEM or adjust ESP usage as needed.

These steps address both the documented ESP-space failure pattern and the specific KB5089549 reliability issue on Windows 11 24H2/25H2 devices.

References:

• Windows 11, version 24H2 known issues and notifications
• Resolved issues in Windows 11, version 24H2
• Windows 11, version 25H2 known issues and notifications
• Resolved issues in Windows 11, version 25H2
• Error with recent windows security update: 2026-05 Security Update (KB5089549) (26200.8457) Error Code: (0x80073712) - Microsoft Q&A