Microsoft has acknowledged an issue with the installation of Windows 11’s May 2026 Update (KB5089549), which has been encountering errors such as 0x800f0922, 0x80240069, and 0x80240031. An emergency server-side update is being implemented to resolve these installation hurdles. The KB5089549 update is mandatory and intended to install automatically on compatible PCs, but some users have reported difficulties, including installation stalling around 35-36%, leading to a rollback with a message stating, “something didn’t go as planned. Undoing changes.”
Investigations reveal that installation failures are particularly affecting devices with limited EFI partition space, with error code 0x800f0922 indicating insufficient free space and potential conflicts with third-party files. The EFI System Partition (ESP) typically occupies no more than 100MB and can become congested due to leftover files, causing installation failures when available space is low. Users with less than 10MB of free EFI storage may face additional complications. A PowerShell command can be used to check EFI storage status.
Microsoft has advised users to consider increasing the size of the ESP by modifying the Windows Registry, although the recent server-side update may have already addressed the issue. The Known Issue Rollback (KIR) has been implemented, automatically propagating the resolution to devices. Users are encouraged to restart their devices to expedite the application of the fix, and there are no additional bugs reported.