Microsoft updated its Windows release-health documentation on May 29, 2026, with a useful fix note for a Windows 11 update problem that could stop the May 2026 security update from installing. The short version: some Windows 11 version 24H2 and 25H2 computers could fail while installing the May security update, roll back, and show error 0x800f0922. Microsoft says the issue is resolved by KB5089573, the May 26, 2026 preview update, and later updates.
This is not a brand-new Patch Tuesday release, and Apple did not publish a new macOS security release today. It is still worth customer attention because failed security updates are one of those problems people ignore until a computer is behind on patches, rebooting repeatedly, or holding up a workday.
What Microsoft Changed Today
Microsoft’s official Windows 11 version 24H2 release-health page and matching Windows 11 version 25H2 release-health page were updated on May 29, 2026. The known issue is listed as resolved, with KB5089573 identified as the resolving update.
The issue started with the May 2026 Windows security update, KB5089549, released May 12, 2026 for Windows 11 builds 26200.8457 and 26100.8457. Microsoft says affected devices could fail during installation because the EFI System Partition, also called the ESP, did not have enough free space. Microsoft specifically calls out devices with 10 MB or less free on that partition.
For customers, the practical symptom is simple: the update may appear to install, the computer restarts, then the installation fails around the reboot phase and rolls back. Microsoft’s release-health text says users may see a message like “Something didn’t go as planned. Undoing changes.” Microsoft also lists log clues in C:\Windows\Logs\CBS\CBS.log, including entries about insufficient ESP free space and boot-file servicing failures.
Who Is Affected
Based on Microsoft’s release-health pages, this issue affects:
- Windows 11, version 24H2
- Windows 11, version 25H2
- Client devices only; Microsoft lists server as not affected for this known issue
- Devices that installed or tried to install the May 2026 security update KB5089549
- Systems where the EFI System Partition has very limited free space, especially 10 MB or less
This will not hit every Windows 11 computer. Many home and business PCs have enough ESP space and will never show this error. The more likely candidates are upgraded systems, OEM images with unusual boot partitions, machines that have accumulated third-party boot files, or devices that have been through several major Windows feature upgrades.
Why This Matters For Home Users And Small Businesses
A failed Windows security update is more than an annoyance. If the update keeps failing, the computer may remain missing important security and reliability improvements. Users may also waste time retrying the same update, rebooting repeatedly, or trying random fixes from search results that do not apply to the actual root cause.
For small businesses, this can create a quiet patch-management gap. One employee may mention that “Windows keeps undoing changes,” while another just keeps postponing restarts. If nobody checks update history, several PCs can drift out of compliance without anyone noticing.
Microsoft’s KB5089549 page also notes May 2026 security-update work around Secure Boot certificates and servicing-stack reliability. That means the usual advice applies: do not treat boot-related update failures casually. Make sure important files are backed up, avoid hard-powering-off a machine while it is actively applying updates, and escalate if the same computer repeatedly fails around the same percentage.
What Customers Should Do Now
If your Windows 11 computer already installed the May updates successfully and is not showing update errors, there is probably nothing special to do beyond normal patching. Keep Windows Update current and restart when prompted.
If your PC is failing with 0x800f0922, check whether KB5089573 or a later update is available for your device. Microsoft says the issue is resolved by Windows updates released May 26, 2026 and later. On a normal home PC, go to Settings > Windows Update, check for updates, and review optional updates if needed.
For managed business computers, do not blindly apply a preview update everywhere just because one machine failed. KB5089573 is a preview update, so IT should weigh the fix against normal testing policy. In many environments, the better path may be to test KB5089573 on affected machines first, then decide whether to deploy it broadly or wait for the next security update that includes the fix.
What Can Go Wrong If You Try To Fix It Yourself
The risky part is that the root cause involves the EFI System Partition. That partition is tied to how Windows boots. Shrinking, expanding, deleting, or manually editing boot partitions without a verified backup can turn a patch problem into a no-boot problem.
Microsoft’s release-health page includes a workaround involving a registry value, and it also discusses Known Issue Rollback for managed devices. Those are official Microsoft options, but they are not casual “click around until it works” fixes. Editing the registry incorrectly can cause system problems. Deploying Known Issue Rollback in a business requires the right Group Policy configuration and a restart.
Before trying advanced fixes, check the basics:
- Make sure the device has a current backup of important files.
- Confirm the exact Windows version and update history.
- Write down the exact error code and when it appears.
- Check whether other computers in the same business are failing too.
- Avoid third-party “partition fixer” tools unless you fully trust the tool and have a recovery plan.
Business IT Rollout Guidance
For businesses, the practical approach is controlled triage:
- Identify affected devices. Look for Windows 11 24H2 or 25H2 machines that failed KB5089549 with 0x800f0922 or rolled back during reboot.
- Separate one-off failures from a pattern. One failed laptop may be local disk or partition history. Multiple failures may mean a device model or image has the same ESP layout.
- Test KB5089573 on affected systems first. Because KB5089573 is a preview release, test before broad deployment.
- Plan restarts. Microsoft notes that recent and upcoming Windows updates may cause an additional restart on some devices because of Secure Boot certificate work.
- Document exceptions. If a device cannot be patched immediately, record why and set a follow-up date.
For customers using Microsoft Intune, Windows Update for Business, WSUS, or another RMM tool, this is a good time to review failed-update reporting. A device that says “pending restart” is different from one that repeatedly fails and rolls back.
What About Apple macOS Today?
I checked Apple’s official Apple security releases page for same-day macOS security releases, Rapid Security Responses, or new macOS security advisory entries. As of this check on May 29, 2026, Apple’s latest macOS-related security entries were still earlier May releases, including macOS Tahoe 26.5, macOS Sequoia 15.7.7, and macOS Sonoma 14.8.7 from May 11, plus Safari 26.5 from May 13. I did not find a same-day macOS security release to include.
When To Call The IT Guys
Call The IT Guys if a Windows 11 computer keeps failing updates with 0x800f0922, keeps rolling back around the restart phase, or shows repeated “Undoing changes” messages. That is especially important for work computers, accounting systems, point-of-sale machines, and laptops that carry customer or business data.
We can check the update history, confirm whether KB5089573 or a later fix applies, review the CBS logs, verify backup status before touching boot-related settings, and help small businesses roll out the fix without turning one failed update into a larger outage.
Official Sources Checked
- Microsoft Windows 11 version 24H2 release health: known issue updated May 29, 2026
- Microsoft Windows 11 version 25H2 release health: matching known issue status
- Microsoft KB5089549: May 12, 2026 Windows 11 security update
- Microsoft KB5089573: May 26, 2026 Windows 11 preview update that resolves the issue
- Microsoft Windows message center
- Microsoft Security Update Guide CVRF updates feed
- Apple security releases