Windows 11 KB5089549: error 0x800f0922 and fix KB5089573

KB5089549 is the May 12, 2026 security update for Windows 11 25H2 and 24H2, builds 26200.8457 and 26100.8457. Microsoft documented an installation failure on some devices and subsequently published a fix. The earlier headline said a fix was still coming; that is now outdated.

The confirmed issue

On some PCs with little free space on the EFI System Partition (ESP), particularly 10 MB or less, setup may fail with 0x800f0922. After initial installation, the restart can fail at around 35–36% and roll back changes. C:\Windows\Logs\CBS\CBS.log may contain SpaceCheck: Insufficient free space and ServicingBootFiles failed. Error = 0x70. Not every 0x800f0922 error has this cause.

A fix is already available

Microsoft says the issue is addressed in KB5089573, a May 26, 2026 preview update for Windows 11 25H2 and 24H2, builds 26200.8524 and 26100.8524. Check Settings > Windows Update for applicable current updates; on managed devices, follow your administrator’s deployment policy. Its preview designation does not call for indefinitely pausing security updates.

If installation still fails

Verify the KB number in Update history, the error code and the logs. Make sure you have a working backup and access to the BitLocker recovery key if encryption is enabled. If failure persists after available updates, consult Microsoft guidance or your administrator before altering boot files or partitions.

Avoid unverified workarounds

The old article recommended changing EspPaddingPercent in the Registry, waiting for an automatic Known Issue Rollback, deleting OEM folders from the EFI partition and disabling antivirus. Microsoft’s current issue page instead points to KB5089573. Do not delete EFI files or change the Registry, security software or partitions on the basis of generic instructions; doing so can break startup or weaken protection.

BitLocker, Search and certificates

KB5089549 includes Microsoft’s fix for certain BitLocker Recovery prompts following the April 2026 update. Reports about Windows Search, graphics drivers and particular laptop models from the earlier article are not presented here as confirmed KB5089549 issues. Microsoft also notes that devices without renewed Secure Boot certificates generally continue to boot and receive normal updates after some certificates began expiring in June 2026.

Official sources

KB5089549 notes: https://support.microsoft.com/en-us/servicing/os/windows-11/2026/05/may-12-2026-kb5089549-os-builds-26200-8457-and-26100-8457 . KB5089573 notes: https://support.microsoft.com/en-us/servicing/os/windows-11/2026/05/may-26-2026-kb5089573-os-builds-26200-8524-and-26100-8524-preview .