Microsoft Releases Windows 11 KB5089573 To Fix May Update Install Failures

Microsoft has released KB5089573, a new optional preview cumulative update for Windows 11 version 25H2 and version 24H2. The update fixes an installation failure that caused some devices to roll back the May 2026 security update with error code 0x800f0922.

The KB5089573 update moves Windows 11 25H2 to build 26200.8524 and Windows 11 24H2 to build 26100.8524. Microsoft released it on May 26, 2026, as a preview update with production-quality improvements.

The fix targets a known issue in the KB5089549 security update, where Windows could fail during the restart phase when the EFI System Partition had too little free space. Microsoft says affected devices were especially likely to hit the problem when the ESP had 10 MB or less available.

What KB5089573 Fixes

The May 2026 security update could install through the early stages and then fail during reboot at roughly 35 to 36 percent. Windows then rolled back the installation and showed the message “Something didn’t go as planned. Undoing changes.”

Microsoft’s Windows release health dashboard lists the issue as resolved by updates released May 26, 2026, and later. That means users who install KB5089573 or a newer update no longer need the older workaround for this specific problem.

The failure was tied to limited space on the EFI System Partition. Microsoft said CBS logs could show entries such as “SpaceCheck: Insufficient free space” and “ServicingBootFiles failed. Error = 0x70,” pointing to the boot file servicing failure.

Item	Details
Update	KB5089573
Release date	May 26, 2026
Windows versions	Windows 11 25H2 and Windows 11 24H2
New builds	26200.8524 and 26100.8524
Main fix	0x800f0922 installation failure caused by limited EFI System Partition space
Update type	Optional preview cumulative update

Why KB5089549 Failed On Some PCs

The original issue came from the May 12 Patch Tuesday release. The May 2026 Windows 11 security update could not complete installation on some systems with limited free space in the EFI System Partition.

The EFI System Partition stores boot-related files. When Windows servicing needs to update boot files and the partition lacks enough space, the process can fail during restart even if the update appears to install normally at first.

Microsoft previously offered two mitigations. Consumer devices and non-managed business devices received relief through Known Issue Rollback, while administrators could apply a registry workaround by setting EspPaddingPercent under HKLM\SYSTEM\CurrentControlSet\Control\Bfsvc.

How To Get KB5089573

Home users can install the update from Windows Update. Microsoft says users should open Start, go to Settings, select Windows Update, then Advanced options, and choose Optional updates. If the update is available, it can be downloaded and installed from there.

Admins and advanced users can also use the Microsoft Update Catalog. The catalog lists KB5089573 packages for Windows 11 24H2 and 25H2 on x64 and Arm64 systems.

Microsoft says this preview update is not included in Windows Update for Business at this stage. The company says the same changes will appear in the next Windows security update for Windows Update for Business deployments.

• Open Settings.
• Go to Windows Update.
• Select Advanced options.
• Open Optional updates.
• Download and install KB5089573 if it appears for your device.
• Restart when Windows asks you to complete installation.

What Else Is Included In The Update

KB5089573 includes more than the EFI System Partition fix. Microsoft also lists reliability improvements for sign-in and lock screens, File Explorer, touch gestures, theme changes in Settings, desktop shortcut loading, Microsoft Store downloads, Task Scheduler column widths, and Times New Roman rendering for Greek and Cyrillic text.

The Windows 11 preview update also refreshes several AI components to version 1.2605.856.0, including Image Search, Content Extraction, Semantic Analysis, and Settings Model. Microsoft notes that these AI component updates apply only to Windows Copilot+ PCs and will not install on standard Windows PCs or Windows Server.

The update also includes Servicing Stack Update KB5092734, build 26100.8519. Microsoft says servicing stack updates improve the component that installs Windows updates, helping devices receive and apply future Microsoft updates more reliably.

Component	Version or change
Image Search	1.2605.856.0
Content Extraction	1.2605.856.0
Semantic Analysis	1.2605.856.0
Settings Model	1.2605.856.0
Servicing Stack Update	KB5092734, build 26100.8519

What IT Admins Should Know

For managed environments, the most important point is deployment timing. Microsoft says KB5089573 is available through Windows Update and the Microsoft Update Catalog, but Windows Update for Business will receive these changes in the next security update.

Organizations that need to fix the 0x800f0922 issue before the next Patch Tuesday can import the package manually from the Update Catalog or use their normal testing and deployment process for optional preview updates.

Admins should also review machines that already failed KB5089549. The Windows release health page says devices that install KB5089573 or later do not need the workaround for this issue.

Microsoft Reports No Known Issues In KB5089573

Microsoft says it is not currently aware of any issues with KB5089573. That does not make the preview update mandatory for every device, but it makes the release important for systems affected by the May update install failure.

Users who do not need the immediate fix can wait for the same improvements to arrive in the next cumulative security update. Users who repeatedly see error 0x800f0922 after installing the May security update should consider KB5089573 sooner, especially if their device has limited EFI System Partition space.

Microsoft also warns that uninstalling this combined package with wusa.exe and the /uninstall switch will not work because the package contains a Servicing Stack Update. Since the SSU cannot be removed after installation, administrators should test the package before broad rollout.

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