Microsoft 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:
