"Disk Not Ejected Properly" when you did not unplug anything: the causes, and what it costs
The warning appears when a drive drops off without being ejected, often while the Mac sleeps. Why it happens, the check it triggers, and how to stop it.
A notification says Disk Not Ejected Properly. Eject "Backup" before disconnecting or turning it off. Often nobody touched the cable. The drive lost its connection, or its power, for a moment, and macOS treats that exactly like being pulled out.
Why it happens when you did nothing
| Cause | Typical sign |
|---|---|
| The Mac's sleep cut power to the port or hub | Happens overnight or after the lid was closed |
| A portable drive is not getting enough power | Bus powered drive through a hub or a long cable |
| A loose or worn cable or connector | Happens when the desk is bumped |
| A hub or dock dropping out | Every drive on the hub disconnects at once |
| The drive itself sleeping or failing | Clicks, or disappears under heavy copying |
What it costs
- Files being written at that moment can be damaged. A copy in progress, or a Time Machine backup, may need redoing.
- The next connection triggers a disk check. macOS checks the file system before mounting. On a large exFAT drive that check can take a long time, and the drive will not mount until it finishes. That is a common cause of the disenter error.
Stopping it
- Plug the drive straight into the Mac rather than through a hub, or use a hub with its own power supply.
- Try a short, good cable. Long or cheap cables are a frequent cause with bus powered drives.
- Check sleep settings. On a desktop Mac, in System Settings, Energy, turn off the option to put hard disks to sleep when possible. On a laptop, eject drives before closing the lid.
- Watch for a pattern. If one drive disconnects and others on the same port do not, suspect that drive or its cable.
After it happens
Run First Aid on the drive in Disk Utility, especially if it holds backups. If it reports errors, see Disk Utility First Aid failed. And if the drive will not eject normally the next time, see disk won't eject.
Common questions
Why does my Mac say Disk Not Ejected Properly when I did not unplug it?
The drive lost connection or power for a moment, often during sleep, through an unpowered hub, or with a loose or long cable. macOS treats that the same as unplugging it.
Is Disk Not Ejected Properly harmful?
It can be. Files being written at that moment may be damaged, and the next connection triggers a disk check that can delay mounting. Run First Aid afterwards.
How do I stop my external drive disconnecting when my Mac sleeps?
Plug it directly into the Mac or a powered hub, use a short good cable, turn off putting hard disks to sleep in Energy settings, and eject drives before closing a laptop.