Industry observers note that microsoft has now acknowledged on this support page that the installation of this important patch fails on some computers—while displaying error code 0x800f0922—if there is insufficient free space on the EFI System Partition (ESP):. Microsoft’s May security patch KB5089549 is failing to install on some Windows 11 machines.
In a fresh development, this issue affects devices with limited free space on the EFI System Partition, especially when the device has 10 MB or less space available. After installing the May 2026 Windows security patch, some devices might experience installation failures with error code 0x800f0922.
In a fresh development, the installation then rolls back with error code, and users might see the message: “Something didn’t go as planned. Undoing changes.”. On affected devices, the installation might proceed through the initial phases but fail during the reboot phase at approximately 35–36% completion.
In a fresh development, resulting from this issue, users may observe log entries similar to the following in C:\Windows\Logs\CBS\CBS.log, indicating insufficient free space on the EFI System Partition:.
As part of the ongoing story, this issue currently affects Windows 11 versions 25H2 and 24H2, but not Windows Server editions.
As part of the ongoing story, microsoft offers two workarounds for affected users.
As part of the ongoing story, this is the safer option for those who don’t have a lot of experience tinkering with Windows system files. One option is to use Known Issue Rollback (KIR) to roll back the problematic patch to a previous version, restoring the system to its state prior to installing the patch.
The report highlights that open the Power User menu with the Windows key + X shortcut, arrival Terminal as Admin, and enter this command:. If you do have experience and admin rights, you can install the patch with a registry tweak.
Industry observers note that reg add "HKLM\SYSTEM\CurrentControlSet\Control\Bfsvc /v EspPaddingPercent /t REG_DWORD /d 0 /f".
According to the latest update, Then restart your PC and try installing the patch again.
Industry observers note that microsoft is working on a permanent fix for this issue and will drop it as part of one of the upcoming Windows updates.
In a fresh development, this article originally appeared on our sister publication PC-WELT and was translated and localized from German.
As part of the ongoing story, he has been writing on almost all IT topics for around 25 years, covering everything from news to reviews and buying guides. Hans-Christian Dirscherl began his IT life with Autoexec.bat and config.sys, Turbo-Pascal and C, Sinix and Wordperfect.