"Disk Not Ejected Properly" on a Mac: why it appears and how to stop it
· 5 min read
“Disk Not Ejected Properly” appears when a drive disappears while macOS still has it mounted, and the message adds “Eject” followed by the drive’s name, “before disconnecting or turning it off.” If you pulled the cable without ejecting, that’s the whole story. If you touched nothing, the drive dropped off the connection by itself, and the usual causes are sleep, too little power, or a poor cable. Check the drive with First Aid, then change one thing at a time.
What the message means
macOS keeps recently written data in memory and writes it to an external drive a little later, so a program can carry on without waiting for the drive. Ejecting tells the Mac to finish those writes and close the drive’s file system cleanly. When the drive vanishes first, any write still waiting is lost, and the file system may be left half updated.
How much that matters depends on the format. Mac OS Extended (Journaled) keeps a journal of changes it can replay after an interruption, and APFS writes changes to new space before switching over, so both usually come back in a consistent state. exFAT and FAT32, the formats common on SD cards and flash drives, have neither, so an interrupted write is more likely to leave a damaged file or a drive that asks to be repaired. APFS, exFAT or Mac OS Extended explains the differences.
Most of the time nothing is wrong. If the drive was idle, files that had finished saving are normally fine. The risk sits with whatever was being copied or saved when it dropped.
Work out which case you have
Ask what happened just before the notice.
- You pulled the cable or card. Eject first next time: click the eject button beside the drive in Finder’s sidebar, or select the drive’s icon, on the desktop or in a Finder window, and press Command-E.
- It appeared right after the Mac woke from sleep. The drive or the Mac’s power to it went down during sleep and didn’t come back cleanly.
- It appears at random while you work. Suspect power or the connection: a hub, a dock, a loose plug, a worn cable.
- It happens with only one drive. The drive or its enclosure is the likelier fault.
To see whether the Mac currently sees the drive, run:
diskutil list external physical
The word physical leaves out disk images, which macOS also counts as external. If your drive is listed, the Mac can see it. If nothing prints while the drive is plugged in, the connection is down right now.
Cause one: sleep
Many external hard drives spin down to save power, and some enclosures cut power when the Mac sleeps. On wake the drive has to start again, and if it doesn’t come back cleanly, macOS treats it as removed.
On a Mac laptop, open System Settings, click Battery, then Options, and look for Put hard disks to sleep when possible. Turning it off stops the Mac asking drives to spin down. Apple’s Energy settings page for desktop Macs doesn’t list this option on current versions of macOS, so a Mac mini, iMac or Mac Studio may not show it; the power and cable fixes below matter more there.
The setting is about hard disks, the spinning kind. A solid-state drive has nothing to spin down, but a bus-powered one can still lose power during sleep, which the next cause covers.
Cause two: not enough power
Bus-powered drives draw all their power through the cable. A hub, a dock or a port shared with other busy devices may not supply enough, and the drive resets under load, often in the middle of a big copy.
- Plug the drive straight into the Mac, with no hub or dock.
- If it needs a hub, use one with its own power supply.
- Try a different port on the Mac. If the drops follow one port, stop using it for drives.
Telling the ports apart helps if you aren’t sure which socket does what.
Cause three: cable or enclosure
A cable that works for charging may not be reliable for data. Swap in a different, short cable, ideally the one that came with the drive. If the drop follows the cable, replace it. If it follows the drive on a different Mac too, the enclosure or the drive itself is failing, so copy your files off now while it still mounts.
After an unexpected drop
Run First Aid before you trust the drive again.
- Open Disk Utility (in Applications, then Utilities).
- Select the drive’s volume in the sidebar.
- Click First Aid, then Run.
First Aid checks the file system and repairs what it can. If it fails, First Aid process has failed covers the next steps. Open the files you were working with and check they’re intact, since a partly written file can still open and be damaged.
What not to do
Don’t ignore repeated notices on a drive that holds the only copy of something. Each drop is a chance for damage, and a fault that appears twice usually appears a third time. And if the drive mounts again by itself after the notice, eject it properly before you unplug it, so you don’t add a second interruption. If macOS says it can’t eject because something is using it, see the disk wasn’t ejected because programs may be using it.
Questions
Why does “Disk Not Ejected Properly” keep popping up? Something is making the drive drop repeatedly. The common causes are the drive spinning down during sleep, a hub or dock that can’t supply enough power, or a worn cable. Plug the drive directly into the Mac with a different cable and see whether the notices stop.
Why do I get “Disk Not Ejected Properly” when my Mac goes to sleep? The drive or its power was cut while the Mac slept, so the drive wasn’t there when the Mac woke. On a laptop, try turning off “Put hard disks to sleep when possible” in Battery settings under Options, and plug the drive in directly rather than through a hub.
Can I lose data when a disk isn’t ejected properly? Yes, but only data that was being written at that moment, and sometimes the file system’s own records. Finished, idle files are normally fine. Drives formatted exFAT or FAT32 are more exposed than APFS or Mac OS Extended drives. Run First Aid and check recent files.
Does the notice appear for SD cards too? Yes. An SD card is a disk to macOS, so pulling it out without ejecting gives the same message. Cards are usually exFAT or FAT32, so eject them before removing them.