Microsoft has acknowledged a significant issue with the May 2026 Windows 11 security update, identified as KB5089549. Users have reported difficulties in installing the update, with many encountering the 0x800f0922 error code. This complication arises primarily due to insufficient free space on the EFI System Partition (ESP), which leads to the update being rolled back on affected systems.
Understanding the Issue
The company noted that devices with limited free space on the ESP, particularly those with 10 MB or less available, are most susceptible to this problem. During the installation process, the update may appear to progress smoothly until it reaches the reboot phase, where it typically fails at around 35–36% completion.
For those experiencing these installation setbacks, a common notification reads, “Something didn’t go as planned. Undoing changes.” Additionally, users may find log entries that indicate insufficient ESP free space, including:
- “SpaceCheck: Insufficient free space”
- “ServicingBootFiles failed. Error = 0x70”
- “SpaceCheck: used by third-party/OEM files outside of Microsoft boot directories”
Mitigation Strategies
While Microsoft is actively working on a resolution, the company has recommended that affected users utilize the Known Issue Rollback feature. This Windows capability allows users to reverse problematic updates that have been deployed via Windows Update.
In enterprise environments where IT departments manage Windows updates, administrators can take proactive steps by installing and configuring the relevant Group Policy. Microsoft emphasized the need for IT teams to implement this policy to address the issue effectively. They stated, “You will need to install and configure the Group Policy for your version of Windows to resolve this issue. You will also need to restart your device(s) to apply the group policy setting. Note that the Group Policy will temporarily disable the change causing this issue.”
For detailed instructions on deploying and configuring the Known Issue Rollback group policies, users can refer to Microsoft’s support website.
Last week, Microsoft rolled out the KB5089549 cumulative update, which included numerous bug fixes, security patches, and enhancements. This release also addressed another known issue that had caused certain Windows 11 systems to boot into BitLocker recovery following the installation of the April 2026 Windows security updates.
Earlier this month, the company resolved a Windows Autopatch bug that inadvertently deployed driver updates restricted by administrative policies on some Autopatch-managed Windows devices within the European Union. Additionally, Microsoft confirmed that the April 2026 security updates had led to failures in third-party backup applications that relied on a vulnerable driver.
