System Updates · October 16, 2026 · ComputerKing Team
Thought You Had a Backup? Windows File History Stopped Backing Up After the September Update — 4 Steps to Verify Yours Really Works
Microsoft's September security update KB5124008 silently stopped File History backups on some Windows PCs, with a false "Reconnect your drive" warning. The fix shipped September 22 and in the October update — but did your backup have a gap? 4 verification steps.
What happened: the September update silently stopped File History
The Windows security update KB5124008, released on September 8, 2026 (Windows 11 24H2 / 25H2), left File History — Windows' built-in backup feature — unable to create or update backups on some PCs. Microsoft later confirmed the problem.
The nastiest part: File History runs automatically in the background. When it stopped, it did not shout about it. You believed it was backing up your files every day — when in fact nothing was being backed up for that period.
There was also a false warning: Windows could pop up "Reconnect your drive", making you think your external hard drive had failed. In most cases the drive was perfectly fine — the bug was in the update itself.
Other symptoms: the "Last backup" timestamp stopped moving; older files showed "No previous versions available"; Event Viewer logged errors referencing FileHistory.exe.
The good news: the bug mainly stopped *new* backups — it did not delete backups you had already made. The fix shipped on September 22 (KB5124010, Windows 11 24H2 / 25H2), and the October cumulative update KB5127648 also includes it. So a fully updated PC should have working File History again — but whether your backups had a gap in the meantime is something you need to check yourself. For what else the October update fixed, see our companion guide, Windows October Update Fixes 1,400+ Flaws!.
4 steps to verify: is your backup actually working?
1. Check the "Last backup" date. Control Panel → System and Security → File History. Is "Last backup" within the last few days? If it is still stuck in early September, you had a gap.
2. Try restoring one file. On the same screen, click "Restore personal files" and see whether you can find and restore an older version of a file. If you cannot, the backup is incomplete.
3. Check Event Viewer. Event Viewer → Windows Logs → Application, and look for FileHistory.exe errors. Errors still appearing mean the problem is not fully resolved.
4. Install the latest cumulative update and run a full backup. Install the latest update from Windows Update (the October cumulative update includes the fix), then click "Run now" in File History to make sure a complete backup runs.
Do not rely on a single backup: the 3-2-1 rule
| Rule | Meaning | Example |
|---|---|---|
| 3 | Keep at least 3 copies of important data | Original + 2 backups |
| 2 | Store them on 2 different media types | External drive + cloud |
| 1 | Keep 1 copy off-site | Cloud / away from home |
File History only backs up Documents, Pictures, Music, Videos and Desktop — not the whole system. For full-machine recovery you need a system image or a third-party backup tool.
Why "uninstall the update" is the wrong fix
Some online guides tell you to uninstall KB5124008 to fix File History. That also removes the security patches that update contained — fixing your backup by opening a security hole. The correct direction is to update *forward* (KB5124010 or a newer cumulative update), not roll back.
How we can help
ComputerKing offers a free backup check:
- 💾 Backup check: confirm File History is actually running, and when your last backup was
- 🔄 Restore test: restore one file on the spot to prove the backup really works
- ☁️ 3-2-1 backup setup: external drive + cloud dual backup, so one failure never leaves you with nothing
- 🖥️ System image backup: full-machine backup, so even a dead hard drive can be restored
📞 WhatsApp 2115 9219 to book, or visit us at Room 1209, 18 On Lai Street, Shek Mun, Sha Tin (Dalit Plaza).
*Last updated: October 16, 2026. Written by the ComputerKing Team. KB numbers and fix dates follow Microsoft's published information.*
Frequently Asked Questions
What is File History?
Windows' built-in automatic backup: it regularly copies Documents, Pictures, Music, Videos and Desktop to an external drive or network location, and keeps older versions so you can recover a file you changed or deleted by mistake.
How do I know if I was hit by this bug?
Three signs: KB5124008 in your update history; "Last backup" in File History stuck in early September; a false "Reconnect your drive" warning even though the drive works fine in File Explorer.
Are my old backup files gone?
No. The bug mainly stopped new backups — it did not delete backups already made. After the fix, your old backups should still be there; check with "Restore personal files".
What backup methods exist besides File History?
Cloud sync (OneDrive / Google Drive), manual copies to an external drive, and system image backups. The safest approach is the 3-2-1 rule: 3 copies, 2 media types, 1 copy off-site — never rely on a single method.