Microsoft has identified the root cause of installation issues related to the May 2026 update for Windows operating system and is rolling out a solution through an optional update, KB5089573. The May 12, 2026, Patch Tuesday update (KB5089549) introduced enhancements but many users faced installation failures due to error code “0x800f0922,” indicating insufficient space on the EFI System Partition (ESP). The ESP is critical for boot files and typically occupies around 256MB. Users can check ESP storage using a specific command. Low ESP space can lead to update failures, particularly when it drops below 10MB. Microsoft has rolled back problematic code and provided a fix in the optional update KB5089573, which resolves ESP space issues and ensures future updates will proceed smoothly. Users are encouraged to install this update or wait for the next scheduled Patch Tuesday update on June 9, 2026.