Microsoft has resolved a known issue causing installation failures and 0x800f0922 errors when deploying the May 2026 Windows 11 security update (KB5089549).
As Microsoft explained when it acknowledged the issue two weeks ago, these failures are caused by insufficient free space on the EFI System Partition (ESP), which results in the update automatically rolling back on impacted devices.
Users affected by these installation problems see a "Something didn't go as planned. Undoing changes." message when the update rolls back, and may also find "SpaceCheck" and "ServicingBootFiles failed" log entries pointing to insufficient ESP free space.
"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."
On Friday, the company said the issue has been resolved in the Windows 11 KB5089573 preview cumulative update, with the fix to be made available to all users who install the June Patch Tuesday updates later this month.
