Microsoft Fixes Windows 11 Update Failures Caused by Small EFI Partitions

Microsoft released Windows 11 cumulative update KB5089573 to permanently fix an installation bug introduced by KB5089549 that caused some systems running versions 24H2 and 25H2 to fail during reboot. Affected devices typically stalled at about 35–36% completion, rolled back the update, and returned error 0x800f0922, with logs indicating insufficient free space in the EFI System Partition (ESP). Microsoft had already applied a Known Issue Rollback and provided a registry-based workaround for enterprise administrators before issuing the permanent fix.

The update raises Windows 11 builds to 26100.8524 and 26200.8524, includes servicing stack and AI component updates, and is available through Windows Update, Microsoft Update Catalog, Windows Update for Business, and WSUS. Microsoft said no known issues were identified at release and indicated that the fix will also be included in subsequent cumulative updates, reducing the need for users and administrators to manually resize the ESP or remove security updates.