GoKawiilMicrosoft has confirmed that the May 2026 Windows 11 security update (KB5089549) fails to install on some systems and triggers 0x800f0922 errors.
This known issue is caused by insufficient free space on the EFI System Partition (ESP), which results in the update automatically rolling back on affected devices.
"This issue affects devices with limited free space on the EFI System Partition (ESP), especially when the device has 10 MB or less space available," Microsoft said.
"On affected devices, the installation might proceed through the initial phases but fail during the reboot phase at approximately 35–36% completion."
Users impacted by these installation problems also see the "Something didn't go as planned. Undoing changes." message when the installation rolls back, and may find log entries pointing to insufficient ESP free space, such as:
"SpaceCheck: Insufficient free space"
"ServicingBootFiles failed. Error = 0x70"
"SpaceCheck: <value> used by third-party/OEM files outside of Microsoft boot directories"
While Microsoft is still working to resolve this issue, it advised affected customers to mitigate it using the Known Issue Rollback (a Windows feature that reverses buggy updates pushed via Windows Update).
In enterprise-managed environments where IT departments control Windows updates, admins can manually mitigate it by installing and configuring this Group Policy.
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