Microsoft Confirms Windows 11 KB5089549 Installation Failures
Summary
Microsoft says KB5089549 can fail on Windows 11 devices with limited EFI System Partition space, causing 0x800f0922 errors and rollback. Known Issue Rollback or Group Policy can temporarily mitigate the problem.
Key points
- The May 2026 Windows 11 update KB5089549 may fail on devices with limited free space in the EFI System Partition, particularly those with 10 MB or less.
- Affected installations can fail during reboot at about 35–36% completion, show error 0x800f0922, and roll back.
- Microsoft recommends Known Issue Rollback for affected devices; enterprise administrators can apply a Group Policy setting as a temporary mitigation.
- Microsoft says it is still working to resolve the issue.
Article Details
- Event Type
- Windows 11 security update installation issue
- Impact
- The May 2026 update KB5089549 may fail during reboot on systems with insufficient free space on the EFI System Partition, causing a rollback and 0x800f0922 errors. Microsoft advised using Known Issue Rollback or Group Policy settings as temporary mitigations.