Microsoft has confirmed that the May 2026 Windows 11 update KB5089549 can fail to install on some devices because the EFI System Partition does not have enough free space. Affected systems may roll back during reboot with 0x800f0922 errors and can be temporarily mitigated using Known Issue Rollback or Group Policy settings. #Windows11 #KB5089549 #EFISystemPartition #KnownIssueRollback
Keypoints
- KB5089549 may fail to install on some Windows 11 systems.
- The issue is caused by insufficient free space on the EFI System Partition.
- Installations can fail during reboot at about 35–36% completion.
- Affected devices may show 0x800f0922 and rollback messages.
- Microsoft recommends Known Issue Rollback or Group Policy mitigation.