"Disk Not Ejected Properly" on Mac: Causes and Fixes

"Disk Not Ejected Properly" means macOS lost the connection to a drive while it was still mounted. If you didn't unplug anything, the drive dropped off by itself, and the cause is almost always one of four things: the Mac or the drive going to sleep, a USB hub or dock, a cable or power problem, or (rarely) a failing drive. The message itself does no harm. A disconnect in the middle of a write can, so after fixing the cause, check that the files on the drive are intact.

What Does "Disk Not Ejected Properly" Mean?

macOS shows the alert whenever a mounted drive disappears without being ejected first. Ejecting tells macOS to finish writing everything in its cache to the drive and close the filesystem cleanly. When the drive vanishes instead, anything still waiting to be written may not have made it.

If you pulled the cable, the message is expected; eject first next time. If you didn't, and especially if the alerts pile up overnight or after the Mac wakes, the drive is disconnecting on its own. That's the case the rest of this page fixes.

Why Does My Mac Keep Saying "Disk Not Ejected Properly"?

1. Sleep (the most common cause)

When a Mac sleeps, it cuts power to USB ports or spins drives down, and some drives and enclosures don't come back cleanly on wake. You get one alert per volume each time it happens, which is why people find a stack of them in the morning.

Check what your Mac is set to. In Terminal:

pmset -g | grep disksleep

On the MacBook Pro I tested on (macOS 15.5), the default was disksleep 10, meaning macOS spins drives down after 10 minutes of inactivity, on both battery and power adapter.

To stop it:

• Desktop Macs (iMac, Mac mini, Mac Studio): System Settings → Energy. Turn off Put hard disks to sleep when possible, and turn on Prevent automatic sleeping when the display is off.
• MacBooks: System Settings → Battery → Options. Turn off Put hard disks to sleep when possible, and turn on Prevent automatic sleeping on power adapter when the display is off.
• Or in Terminal, for all power sources:

sudo pmset -a disksleep 0

Seagate's support page for this error recommends the same settings, and notes that the drive can still disconnect if you put the Mac to sleep manually. On a MacBook on battery, sleep is hard to avoid entirely, so eject drives before closing the lid.

2. A USB hub, dock, or monitor port

Hubs and docks are the second most common cause. They lose power or reset briefly when the Mac sleeps or wakes, when the monitor they're built into turns off, or when another device draws too much current. Every drive behind them disconnects at once.

Test by plugging the drive straight into a port on the Mac. If the alerts stop, the hub is the problem. A powered hub (with its own power adapter) is more reliable than an unpowered one for drives.

3. The cable or power supply

A cable that's slightly loose or damaged can drop the connection for a split second, which is enough. Try a different cable, ideally a short one. Portable 2.5-inch hard drives draw their power from the port; an unpowered hub or a long, thin cable can leave them underpowered, especially while spinning up. Desktop drives with their own power brick can disconnect when the brick fails or shares a power strip with something that trips it.

4. The drive's own sleep timer

Many external drives (WD, Seagate, LaCie and others) have their own power-saving timer in the enclosure, separate from macOS. Some don't wake reliably on a Mac. The manufacturer's utility, where one exists for macOS, can usually turn it off or lengthen it.

5. A macOS bug on 2023 Mac Pro internal drives

Apple has a support article for one specific case: certain internal SATA drives in the 2023 Mac Pro disconnecting after the Mac wakes from sleep. The fix is to update to macOS Ventura 13.5 or later (Apple Support). If you're seeing the alert after a different macOS update, check whether a newer point release is available; this alert has come and gone with macOS bugs before.

6. A failing drive

If the drive disconnects while you're actively using it, makes new clicking or grinding sounds, or copies keep failing partway, the drive itself may be failing. Copy off anything that exists nowhere else before trying repairs. How long external drives last lists the warning signs.

After the Alert: Check Your Files

Most of the time, a disconnect while the drive was idle does no damage. A disconnect during a write is different, especially on exFAT drives, which have no journal to recover from. (APFS vs exFAT explains the difference.)

1. Run First Aid. Open Disk Utility, select the drive's volume, and click First Aid. It repairs filesystem damage from the disconnect.
2. Check anything that was being copied. If a copy or export was running when the alert appeared, assume that file is incomplete. Compare the folder with its source in Terminal:

rsync -anic ~/Projects/Client-Job/ /Volumes/Archive/Client-Job/

Any line starting with >f is a file that differs from the original. Copy those again. In a test on macOS 15.5, a check by size and date missed a damaged file that this content check caught, which is why the -c matters.

1. If the drive was a backup destination, run the backup again once the drive is stable, so it catches up on anything that was interrupted.

Backup tools differ in how they handle a drive that drops mid-transfer. Tusk, for example, pauses the session when a destination disconnects and resumes when it's back, then checks every file's BLAKE3 hash on arrival, so an interrupted copy is retried instead of left half-written.

Can You Turn Off the "Disk Not Ejected Properly" Notification?

macOS doesn't offer a reliable switch to hide this alert, and hiding it would hide the warning that a write may have been cut off. Fix the cause instead: in most cases, turning off disk sleep and connecting the drive directly stops the alerts completely.