May 2026 Windows Update — Known Problems and Fixes

May's Windows update has been out for two days. For most people it installed quietly in the background and that was that. A subset of Windows 11 PCs are having a harder time — the update downloads, starts installing, and then reverses itself on restart. Here's what's happening.

Update failing to install — rolls back with an error

The May 2026 cumulative update for Windows 11 is KB5089549, released on 12 May. On some machines running Windows 11 version 24H2 or 25H2, it fails during the installation step and rolls back. You'll see: "Something didn't go as planned — undoing changes. Please keep your computer on."

After that, Windows restarts and everything goes back to how it was before. The PC works fine. The update just didn't take.

Most rollbacks are clean. The problem cases are mainly HP laptops and other devices where the EFI partition — a small hidden partition Windows uses during boot — has almost no space left. Windows needs to write new boot files as part of installing the update, and if that partition is full, it can't. On a handful of HP devices, this has left the PC unbootable rather than rolling back cleanly.

Microsoft hasn't acknowledged the issue yet. Their Known Issues page lists nothing for KB5089549.

What to do

If your PC rolled back and is working normally:

1. Don't panic. The rollback is doing what it's supposed to — protecting you from a bad install.
2. Leave Windows to try again on its own. It will retry the update automatically. Don't go to the Microsoft Update Catalog and manually download KB5089549 — you'd hit the same problem.
3. Check back in Settings > Windows Update in a few days. Either Microsoft will push a corrected version, or the automatic retry will eventually succeed.

If your PC is stuck — not starting up properly after the failed update:

1. Hold the power button until the PC turns off completely. Wait 10 seconds.
2. Turn it back on. If it starts normally, you're fine — see the steps above.
3. If it doesn't start: when the PC is turning on, hold Shift and click Restart from the login screen if you can get to it, or turn the PC off and on three times in a row — Windows will automatically enter recovery mode after repeated failed boots.
4. From the blue recovery screen, go to Troubleshoot > Advanced options > Startup Repair and let it run.
5. If that doesn't sort it, go back to Advanced options > Uninstall Updates > Uninstall latest quality update to remove the partially-installed update.

If your PC won't start at all and recovery mode won't load, a computer repair is the quickest route — trying to rebuild a broken boot environment without the right tools is slow going.

Should you still install the update?

Yes, when it works. This month's patch fixes 120 vulnerabilities, including some nasty ones in Microsoft Word where an attacker can run code on your machine just by you previewing a dodgy file in File Explorer or Outlook. You don't have to open it. That's the kind of thing that ends up weaponised quickly.

The people hitting the rollback are a minority. Most Windows 11 PCs have taken KB5089549 without any trouble.

If yours keeps rolling back, sit tight. Don't force it. Windows will handle it when Microsoft pushes an updated version of the package, or when you have enough disk space freed up that the update can succeed. In the meantime, your PC is no worse off than it was before Patch Tuesday.

Mark

Mark has been fixing computers since the late '90s and went self-employed in 2008. Based in St Helens since 2013, he works evenings and weekends from his home in Laffak — friendly, affordable repairs for PCs, laptops, and Macs. See reviews on Google