Microsoft confirmed on June 1, 2026 that its May Windows 11 security update has been failing to install on a chunk of PCs, leaving systems stuck at roughly 35% during the reboot and rolling back with the message 'Something didn't go as planned.' The company has now released an optional fix, KB5089573, and says the patch will also be folded into the June 9 Patch Tuesday update — so York-area PC owners who have been wrestling with a failing update this past week finally have a clear path forward.
What's actually broken
The problem affects the May 2026 Patch Tuesday update, KB5089549. Affected users were unable to install the mandatory update due to a vague error code, 0x800f0922, which usually occurs when your device has limited free space on a partition called the EFI System Partition, also known as ESP. ESP is required because Windows uses it to read boot files, and UEFI firmware depends on a specific FAT32-formatted partition (the ESP) that contains the Windows Boot Manager. You can't boot your PC without it. It's always created automatically when you set up Windows and hidden in File Explorer because it's a sensitive partition.
When the EFI System Partition runs out of space, Windows updates can fail due to a recent change. This issue was introduced with Windows 11's May 2026 Update, and Microsoft told reporters it immediately rolled back the buggy code via a server-side update.
The visible symptom is the part that drives people to a computer repair shop: Windows updates would still download properly, but when you reboot the device to finish applying changes, it would get stuck at approximately 35–36% completion. At that point, you'll see the spinning circle screen, and Windows will attempt to roll back the changes, ending with the message 'Something didn't go as planned.'
Microsoft's fix, explained
Microsoft now advises users who are experiencing installation problems with May update KB5089549 to install the optional update KB5089573, which should resolve the issue. If you don't want to install it, you can wait until the next Patch Tuesday on June 9, as Microsoft plans to include the fix for this problem in that upcoming mandatory update.
KB5089573 is optional because it's a preview update. You must therefore install it manually via Windows Update → Advanced options → Optional updates, or download it from the Microsoft Update Catalog.
In Microsoft's own words on its support page, "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."
Why this matters more than a normal update bug
Normally a failed monthly patch is annoying but not urgent. This time it is, because June is also the month Microsoft starts rotating expiring Secure Boot certificates. Organizations are advised to update Windows Secure Boot certificates to their 2023 counterparts ahead of the deadline, when the 2011-issued certificates are set to expire. Devices failing to receive these updates before the June 26 deadline face catastrophic boot-level security failures or degraded security states.
In other words, a PC that can't successfully apply this month's updates is also a PC that may miss the boot-security refresh rolling through Windows Update. If your machine has been stuck in a reboot-rollback loop, that's worth resolving now rather than later — and if the update failure has already corrupted files or left a drive in a bad state, our team can recover data from a drive that won't boot cleanly.
What to do if your PC has been stuck
Quick checklist for non-technical users:
1. Open Settings → Windows Update → Advanced options → Optional updates. Look for KB5089573 and install it. 2. Reboot and let Windows finish applying it. 3. Then re-run Windows Update. The May security update should now install cleanly, and the June 9 cumulative will follow. 4. If you'd rather wait, you can skip the optional update — all future updates will also include the fix for Windows Update failures, so you can skip it and still receive the fix in the next Patch Tuesday update, scheduled for June 9, 2026.
If your PC won't boot at all after a failed update, don't keep power-cycling it — repeated hard shutdowns during a partial update can damage the file system. A no-boot Windows machine usually needs hands-on diagnosis at a local repair shop to recover safely without losing files.
What This Means for York, PA
If your Windows 11 PC has been hanging at 35% during a restart this past week, or throwing the 0x800f0922 error, this is the bug — and there's now a fix. York-area customers who don't want to troubleshoot it themselves can drop the machine off at York Computer Repair (2069 Carlisle Rd) and we'll get the update applied and Secure Boot status verified before the June 26 deadline.