Microsoft fixes KB5089549 Windows security update install issues
Microsoft has resolved a known issue causing installation failures and 0x800f0922 errors when deploying the May 2026 Windows 11 security update (KB5089549).
As Microsoft explained when it acknowledged the issue two weeks ago, these failures are caused by insufficient free space on the EFI System Partition (ESP), which results in the update automatically rolling back on impacted devices.
Users affected by these installation problems see a “Something didn’t go as planned. Undoing changes.” message when the update rolls back, and may also find “SpaceCheck” and “ServicingBootFiles failed” log entries pointing to insufficient ESP free space.
“This issue affects devices with limited free space on the EFI System Partition (ESP), especially when the device has 10 MB or less space available,” Microsoft said. “On affected devices, the installation might proceed through the initial phases but fail during the reboot phase at approximately 35–36% completion.”
On Friday, the company said the issue has been resolved in the Windows 11 KB5089573 preview cumulative update, with the fix to be made available to all users who install the June Patch Tuesday updates later this month.
“This issue was resolved by Windows updates released May 26, 2026 (KB5089573), and later. We recommend you install the latest update for your device as it contains important improvements and issue resolutions, including this one,” Microsoft added in a Windows release health dashboard update.
“If you install an update released May 26, 2026 (KB5089573) or later, you do not need to use a workaround for this issue. If you are using an update released before this date, and are experiencing this issue, you can use the following workaround.”
However, those who don’t want to install the May 2026 optional update to address this issue can mitigate it using Known Issue Rollback, a Windows feature that reverses buggy updates pushed via Windows Update.
In enterprise environments managed by IT departments, admins can manually mitigate this known issue by installing and configuring this Group Policy.
You can also find further guidance on deploying Known Issue Rollback group policies on Microsoft’s support website.
Microsoft released the KB5089573 preview cumulative update for Windows 11 versions 25H2 and 24H2 on Wednesday, May 26, with 30 changes, including performance and reliability improvements.
Earlier this month, Microsoft also confirmed that the April 2026 security updates were causing failures in third-party backup applications that used a vulnerable driver, and fixed a Windows Autopatch bug that caused driver updates restricted by administrative policies to be deployed on some Autopatch-managed Windows devices across the European Union
