Microsoft has rolled out a new cumulative update, KB5089573, for Windows 11 versions 25H2 and 24H2, targeting a critical installation failure that affected users following the May 2026 Patch Tuesday release.

The update brings OS builds to 26200.8524 and 26100.8524, respectively, resolving a widely reported error that prevented many systems from completing the monthly security update.

The May 2026 Patch Tuesday security update (KB5089549) triggered installation failures on a subset of Windows 11 devices, with error code 0x800f0922 halting the process.

The failure specifically targeted devices with limited free space on the EFI System Partition (ESP), particularly those with 10 MB or less available. Affected systems would progress through the initial installation phases but crash during the reboot phase at approximately 35–36% completion, leaving devices in an inconsistent state.

Microsoft had previously issued a Known Issue Rollback (KIR) as a temporary workaround, automatically propagating relief to consumer and non-managed business devices.

An alternative registry-based workaround — modifying the EspPaddingPercent value under HKLM\SYSTEM\CurrentControlSet\Control\Bfsvc — was also available for enterprise admins. However, KB5089573, released on May 26, 2026, permanently resolves the issue and eliminates the need for either workaround.

KB5089573 – Cumulative Update

Beyond the critical ESP fix, KB5089573 is a production-quality cumulative update delivered via two phases: a gradual rollout for staged device delivery and a normal rollout for broad general availability. The update incorporates several notable components:

AI Component Refresh: Image Search, Content Extraction, Semantic Analysis, and Settings Model are all updated to version 1.2605.856.0, reflecting Microsoft’s continued push to deepen on-device AI capabilities in Windows 11.
Personalization Improvements: Added on May 28, 2026, as part of the gradual rollout phase.
Servicing Stack Update (KB5092734): Build 26100.8519 improves the reliability and robustness of the Windows update installation infrastructure itself, ensuring devices can cleanly receive future patches.

The update is available through multiple channels with no prerequisites beyond having a compatible Windows 11 25H2 or 24H2 device:

Navigate to Start → Settings → Windows Update → Advanced options → Optional updates
Select the available update and click Download and Install
Alternatively, download the standalone package directly from the Microsoft Update Catalog using the KB number
Enterprise environments can be deployed via Windows Update for Business or WSUS

Microsoft has confirmed there are no known issues with KB5089573 at the time of release.

Should removal be necessary, Microsoft advises using the DISM /online /get-packages command to identify the package name, followed by the DISM/Remove-Package option with the LCU package name as the argument.

Notably, running the Windows Update Standalone Installer (wusa.exe) with the /uninstall switch will not work because the combined package includes the Servicing Stack Update (SSU), which cannot be removed post-installation. Microsoft strongly recommends against removing security updates given the inherent risk exposure.

Given the critical nature of the ESP space issue impacting a broad segment of enterprise and consumer devices, IT administrators and end users alike are advised to prioritize KB5089573 during their next maintenance window.

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