Windows 11 Security Update May Fail Due to Boot Partition Space Shortage
Microsoft's May 2026 security update encounters installation failures due to insufficient free space on the EFI system partition.
New Issue Arises with Microsoft’s May Security Update
Microsoft has acknowledged that its May 2026 security update may fail to install under certain conditions. The affected users are those running Windows 11 versions 25H2 and 24H2.
Cause of the Issue: Insufficient Space on EFI System Partition
The core of the issue lies in the free space of the EFI System Partition (ESP). This partition, typically managed by the operating system, has a minimum recommended size of 200MB. However, when the free space drops below 10MB, the update installation may fail with the error code 0x800f0922.
According to Microsoft’s explanation, “On affected devices, the installation progresses through the initial phases but fails at around 35-36% completion during the reboot phase.” Users are then presented with a message stating, “Something didn’t go as planned. Undoing changes.”
Proposed Solutions and Industry Reactions
In response to this issue, Microsoft has suggested two potential solutions: editing the registry or utilizing the “Known Issue Rollback (KIR)” feature. The company has stated, “This fix has already been automatically distributed to consumer devices and unmanaged business devices.”
The timing of this issue’s emergence coincides with the publication of Microsoft’s blog post titled “Improving Windows Quality,” leading some industry insiders to express skepticism, with comments such as, “Nothing has really changed.” While others have pointed out that shifting the direction of a massive platform like Windows takes time, administrators using KIR Group Policy have voiced concerns about the gap between Microsoft’s claims of quality improvements and the current reality.
Conclusion
This issue highlights the critical nature of security updates, making it a situation that cannot be ignored. Moving forward, Microsoft’s approach to balancing stability and security will be closely watched.
Frequently Asked Questions
- What is the EFI System Partition?
- The EFI System Partition (ESP) is a partition used by UEFI-based computers during boot. It is typically created by the OS installer and stores critical files like boot loaders. In this case, the security update fails when the free space on this partition is insufficient.
- What can I do if this issue occurs?
- Microsoft has proposed two solutions: editing the registry or applying the "Known Issue Rollback (KIR)." For consumer devices and unmanaged business devices, the fix has already been automatically distributed. For more details, it is recommended to consult Microsoft's official documentation.
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