Introduction
The May 2024 security update from Microsoft has left some Windows 11 users in a frustrating loop: attempting to install the patch, seeing it reach around 35–36% completion during reboot, and then encountering the message "Something didn’t go as planned. Undoing changes." This failure leaves systems exposed to the dozens of vulnerabilities the update was meant to fix.
The Root Cause: Insufficient EFI System Partition Space
The culprit is a lack of free space on the EFI System Partition (ESP). Devices with 10 MB or less of available space on this critical boot partition are most affected. The update proceeds through initial phases but fails during the reboot phase—a point where the system tries to apply changes to the ESP. Microsoft confirmed in a support advisory that this space shortage triggers the failure.
Microsoft’s Official Response
Microsoft has offered two workarounds:
- Modify a Windows registry setting to force the update to install despite the space issue.
- Roll back changes and wait for a future update that resolves the problem.
Neither option is ideal, and consultants warn that the registry fix carries risks if applied without proper testing.
Expert Analysis: Trust in the Update Process
Cybersecurity consultant Brian Levine, executive director of FormerGov, described the failure as a "basic hygiene failure dressed up as a technical issue." He emphasized that the real problem isn’t just storage—it’s the erosion of trust in Microsoft’s update process. Learn more about the root cause. "An update that cannot reliably detect available space on the EFI System Partition is not a small miss," Levine said. "It is a reminder that even mature platforms still struggle with dependency awareness and pre-flight validation."
Recommended Fixes and Cautionary Advice
Increase the EFI Partition Size
Eric Grenier, senior director analyst at Gartner, recommends increasing the ESP to 1.5 GB to ensure future updates succeed and to enable updates to the Windows Recovery Environment. He noted this adjustment should not hamper business needs for usable user space.
Registry Fix with Caution
Grenier advised extreme caution if organizations choose the registry fix. "I would recommend that if an organization wanted to use the modified registry fix that they not only backup the registry beforehand but also test it on some pilot devices before rolling out to the rest of the environment," he said. "Even then, I would do a slow phased rollout to be sure nothing breaks." This type of fix in production, if done incorrectly, could require direct hands-on intervention.
Shared Responsibility: IT Teams and Microsoft
Ishraq Khan, CEO of Kodezi, pointed out that blame falls on both sides. Most IT teams reasonably assume that once Windows Update passes its prechecks and starts installation, Microsoft has already validated system state well enough to avoid a reboot-stage failure. "If ESP space is critical to the update succeeding, the updater should have detected and blocked that condition earlier with a clear remediation message," Khan argued. While IT environments may contribute to partition pressure, the update validation logic should catch such common issues before users see the error. See Microsoft’s official advice.
Conclusion: A Call for Better Pre-Flight Validation
The May 2024 security update failure underscores a gap in Microsoft’s update pipeline. Until the validation checks are improved to account for ESP space, IT administrators should proactively resize partitions or cautiously test registry modifications to keep systems protected.