Windows 11 Update KB5089549 Fails to Install on Devices with Low ESP Space
Apply the Known Issue Rollback group policy to affected devices and restart to mitigate the ESP space issue.
Apply the Known Issue Rollback group policy to affected devices and restart to mitigate the ESP space issue.
Summary
Microsoft confirmed that the May 2026 Windows 11 security update KB5089549 fails to install on systems with insufficient free space on the EFI System Partition (ESP).
The error code 0x800f0922 triggers an automatic rollback during the reboot phase, leaving devices with 10 MB or less free space on the ESP. Users see a rollback message and logs such as 'SpaceCheck: Insufficient free space' and 'ServicingBootFiles failed. Error = 0x70'. Microsoft advises affected customers to apply the Known Issue Rollback group policy, which temporarily disables the problematic change.
Enterprise IT administrators can configure this policy and restart devices to mitigate the issue. The KB5089549 cumulative update also includes fixes for BitLocker recovery failures and a Windows Autopatch bug. Microsoft is working on a permanent fix but has not yet released a patch. The update rollout began last week, and the rollback policy is available on Microsoft’s support site. The issue highlights the need for sufficient ESP free space before applying updates.
Key changes
- KB5089549 fails to install on devices with <=10 MB free ESP space.
- Error 0x800f0922 triggers rollback during reboot.
- Group Policy Known Issue Rollback can mitigate the issue.
- Microsoft released KB5089549 with other security patches.
- The rollback policy temporarily disables the problematic change.
- Enterprise IT can configure the policy and restart devices.
- The issue also affects BitLocker recovery failures.
- Microsoft is working on a permanent fix.