My external disk suddenly stopped mounting on my Mac, and Finder doesn’t show it at all. I’ve already reconnected it and restarted the Mac, but it still won’t appear, and I need help figuring out if this is a macOS issue, a Finder problem, or a failing drive.
I’ve run into this on Macs way too many times. The drive looks dead, Finder shows nothing, and it always seems to happen when you need the files now. Most of the time, the disk itself is still there. macOS is the part refusing to deal with the file system.
Before you touch repair tools, check the boring stuff first. I skipped this once and wasted an hour for no reason.
Try another cable. Use a different USB port. Skip the hub and plug the drive straight into the Mac. Then open Finder settings and make sure external disks are set to show up under General and Sidebar. If the drive light is on, or you hear it spin up, I’d start by assuming the hardware still has a pulse.
The fast fix is formatting the drive. That also wipes it clean. So if the files matter, don’t start there.
What I usually see is minor file system damage. macOS gets picky and refuses to mount the disk at all. When that happens, recovery software tends to work better than trying random repair steps first, because it reads the drive more directly. I’ve had the best luck with Disk Drill. It has picked up drives for me when Disk Utility showed them grayed out, unmounted, or weirdly uninitialized.
If you go down the recovery route, make a byte-to-byte backup first. I learned this the hard way after rescanning a flaky drive until it got worse. A full clone gives you something safer to scan, and you stop hammering the original disk. After that, run the scan, preview what it finds, then copy the good files onto your Mac or another drive. Once your data is out, repairs feel a lot less risky.
If your files are already safe, or you don’t care about them, these are the steps I’d try in order.
1. Show the full device list in Disk Utility
This catches a lot of cases where you’re trying to mount the broken volume instead of the physical disk above it.
1. Open Disk Utility.
2. Click View in the top left, then pick Show All Devices.
3. Select the parent disk, usually the top entry with the maker name like WD or Seagate.
4. Run First Aid on that parent disk.
I’ve seen this fix the partition map and make the drive appear right away.
2. Kill a stuck fsck process
If the drive got unplugged without ejecting, macOS sometimes starts a background file check and then sits there blocking the mount.
1. Open Terminal.
2. Enter sudo pkill -f fsck
3. Press Enter and type your password.
You won’t see the password characters as you type. If fsck was hanging, the disk might mount a few seconds later. I’ve had this one work out of nowhere, which felt dumb after all the other stuff I tried first lol.
3. Reset NVRAM and SMC on Intel Macs
If the ports themselves are acting off, this sometimes clears it up.
For Apple silicon Macs, a normal restart already handles most of this behavior.
NVRAM reset:
1. Shut down the Mac.
2. Turn it back on and immediately hold Option + Command + P + R for around 20 seconds.
SMC reset:
1. Shut down.
2. Unplug power for 15 seconds.
3. Plug it back in.
4. Wait 5 seconds.
5. Power on.
On some Intel MacBooks, use Shift + Control + Option + Power for 10 seconds.
4. Mount it manually in Terminal
Disk Utility sometimes gives up earlier than Terminal does.
1. Open Terminal.
2. Run diskutil list
3. Find your drive identifier, something like disk4s1
4. Run diskutil mount /dev/disk4s1
Swap in your own identifier, obv. If it mounts, Terminal will tell you. If it fails, the error message is often more useful than what the GUI shows. I’ve used those errors to figure out whether the problem was file system damage, permission weirdness, or the wrong partition type.
If none of it works
At that point I’d stop trying to be clever and format the drive, assuming the data is already recovered.
In Disk Utility:
1. Select the drive.
2. Click Erase.
3. Pick APFS for Mac-only use.
4. Pick exFAT if you need the disk to move between Mac and Windows.
This usually fixes logical corruption and gets the drive usable again. The main thing is doing recovery first. I’ve seen people erase first because they were annoyed, then spend the rest of the night trying to claw files back. Not fun.
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If Finder shows nothing, I’d check whether macOS even sees the hardware.
Open System Information, then USB or Thunderbolt. If your drive shows there, the port and enclosure are talking. If it does not, this leans hardware, power, cable, or enclosure board, not macOS. I disagree a bit with @mikeappsreviewer on jumping to file system damage first, because a lot of “won’t mount” cases are dead SATA to USB bridges inside the enclosure.
A few things I’d do next.
Try the drive on another Mac or a Windows PC. This is the fastest split test.
If it appears elsewhere, your Mac setup is the issue.
If it appears nowhere, suspect the enclosure or disk.
If it is an external HDD with its own power supply, check the adapter. Weak power causes weird no-show behavior. Seen it more than once.
If Disk Utility sees only the physical disk size but no volumes, look at the S.M.A.R.T. status if available. Failing or Not Supported through USB is common, so don’t panic if it’s missing.
If the data matters, stop mounting attempts after a few tries. Repeated retries on a failing drive are how things get worse. Disk Drill is a solid next step for Mac if the disk is detected at some level, espeically for pulling files off before you erase or repair anything.
Also worth reading, fixing an external hard drive not mounting on Mac.
I’d add one check neither @mikeappsreviewer nor @sonhadordobosque really leaned on enough: see what the Mac logs say when you plug it in.
Open Terminal and run:
log stream --predicate 'eventMessage contains[c] 'disk''
Then connect the drive and watch for messages like I/O errors, APFS container issues, or “media not present.” That tells you way faster whether macOS is refusing the volume or the hardware is flaking out. Console.app works too if you hate Terminal.
Also, boot into Safe Mode once and test the drive there. If it mounts in Safe Mode but not normally, some background junk, third-party NTFS driver, antivirus, or old kernel extension is probly interfering. That’s more common than people think.
One thing I slightly disagree on: I would not keep running First Aid over and over on a drive that clicks, disconnects, or stalls the system. That’s where people turn a shaky disk into a dead one. If the drive is detected but unstable, I’d go straight to data recovery before “fixing” stuff. Disk Drill makes sense in that case, especially if you just need the files off before doing anything risky.
If the disk is completely absent from Disk Utility, System Information, and diskutil list, that’s usually not Finder being weird. That’s cable, enclosure, power, or the disk itself. If it’s an enclosure, pulling the bare drive and testing it with another adapter can sometimes be the aha moment.
If you want a visual walkthrough, this how to recover a drive that won’t mount on Mac with Disk Drill vid is pretty decent. Not magic, but useful.
One angle I’d check that @sonhadordobosque, @andarilhonoturno, and @mikeappsreviewer only touched indirectly is whether the Mac is suppressing the mount because the disk was marked read-only or “dirty” by another system.
In Terminal, run:
diskutil info /dev/diskX
Swap diskX for the physical disk from diskutil list. Look for:
- Read-Only Media: Yes
- Device Location: External
- File System Personality
- Mount Point: Not mounted
If it shows up as read-only unexpectedly, that can point to hardware degradation, not just macOS being stubborn. I slightly disagree with the idea of trying too many software fixes first if the drive is making the Mac beachball. That usually means I/O trouble underneath.
Another useful check is Activity Monitor. Search for diskarbitrationd. If it is hung or chewing CPU when you connect the drive, force quit it and macOS will relaunch it. Sometimes the mount service itself gets stuck.
About Disk Drill:
Pros:
- Good when the disk is detected but won’t mount
- Can preview recoverable files before you commit
- Helpful if you want data off before erasing
Cons:
- Not useful if the Mac cannot detect the hardware at all
- Scans can be slow on weak or failing drives
- Recovery success depends heavily on the disk’s actual condition
So my split is simple: detected but unmountable, software path and maybe Disk Drill. Not detected anywhere, stop blaming Finder and start suspecting the enclosure, cable, power, or the drive itself.