External hard drive not showing up on Mac: not detected vs not mounting

There are two different problems behind “not showing up”. Either the Mac can’t see the device at all (a cable, power or hardware problem), or it sees the device but can’t mount its contents (a file system problem). Two quick checks tell you which one you have.

By Jishnu Mahanta · Updated 2026-10-20

In short

Open Disk Utility, choose View > Show All Devices, and run diskutil list. Drive listed: it is detected, so the problem is mounting or Finder settings. Not listed anywhere: the Mac can’t see it, so check power, cable and port, then try another computer.

Step 1: is the drive detected?

These checks only look. They don’t change anything on the drive.

Disk Utility. Open it from Applications > Utilities and choose View > Show All Devices. Without this setting, Disk Utility hides the physical drive and shows only mounted volumes.
Terminal. Run diskutil list. It prints every disk the Mac can talk to, with sizes. Find yours by capacity.
System Information. Hold Option and choose Apple menu > System Information. Under USB or Thunderbolt, see whether the drive’s enclosure is listed. Under Storage, see its volumes.

If the drive is not detected anywhere

When the drive is missing from all three, the Mac has no connection to it. File system repairs can’t help. Work through the physical chain:

Power. A 3.5-inch drive needs its power adapter. A 2.5-inch bus-powered drive may need a port that can supply enough current; plug straight into the Mac, not a hub or dock.
Cable and port. Swap the cable first (they fail often), then the port, then the adapter if you use USB-A to USB-C.
Accessory permission. On Mac laptops with Apple silicon, macOS may be waiting for you to allow the accessory. Check System Settings > Privacy & Security > Allow accessories to connect (Apple).
Sound and heat. Listen for spin-up. Clicking, repeated spin-ups, or a very hot enclosure mean stop.
Another computer. Try it on a different Mac or on Windows. If no computer sees the drive, the drive, enclosure or its bridge board has failed. If another computer sees it, the problem was your Mac, port or cable.

If a drive is silent, clicking, or gets hot and won’t show up on any computer, don’t keep powering it on. Software can’t fix hardware. A professional data recovery lab is the realistic next step, and the cost depends on the damage.

If the drive is detected but not mounted

You see the disk in diskutil list or Disk Utility, but its volume is greyed out or absent in Finder. Then:

Click Mount in Disk Utility. If you get “Could not mount”, see “Could not mount”: com.apple.DiskManagement.disenter error.
Check Finder isn’t hiding it. Finder > Settings > General: tick External disks. Sidebar: tick External disks.
Check the format. diskutil list shows the type. Linux Filesystem (ext4) or a Microsoft partition with BitLocker can’t be mounted by macOS. The drive isn’t broken; it needs a tool that reads that format. Retrova reads ext4, and opens BitLocker when you have the password or 48-digit recovery key.
If macOS says it isn’t readable, click Ignore, not Initialize: “The disk you inserted was not readable”: click Ignore, not Initialize.
First Aid is Apple’s repair step. It writes to the drive. If files matter, copy first. If it fails, see Disk Utility First Aid failed (exit code 8).

Copy your files off with Retrova

This works for the second case (detected, not mounting). Retrova reads the drive directly and read-only, so it doesn’t depend on macOS mounting the volume. It understands APFS, Mac OS Extended (HFS+), NTFS, FAT12/16/32, exFAT, ext2/3/4, XFS and Btrfs.

Plug the drive in and open Retrova. On the home screen choose A drive won’t open. Retrova lists every drive and partition it can see, with the file system it detected.
Pick the drive or partition. macOS asks for your administrator password at this point, because reading a disk directly needs it. Retrova only uses it to read.
Browse and choose what you want back. If the file system is readable you see your original folders and file names, and you can preview photos, videos, PDFs and text before copying.
Choose a destination on a different drive with enough free space. Retrova never saves onto the drive it is reading.
Copy, then Verify. Files are written as temporary parts and renamed only when complete. When it finishes, run Verify to compare every copy with the original, byte for byte.

If no file system is recognised, or the one it finds is too damaged to list files, run Deep scan from I deleted something. Deep scan ignores the file system and searches the raw drive for the start of 72 known file types (photos including camera RAW, videos, audio, documents, archives, mail files and more). It only recovers files that were stored in one piece, and the original names and folders are lost: finds come back sorted by type with new names.

What Retrova can’t do: it can’t undelete files with their names on APFS, ext or other file systems (only NTFS, FAT and exFAT), can’t open an encrypted drive without its password or recovery key, can’t open the startup disk of a T2 or Apple silicon Mac away from that Mac, doesn’t handle RAID sets or phones, and can’t fix a drive with physical damage. Retrova’s builds aren’t signed or notarised yet, so macOS and Windows will show a warning the first time you open it.

If the drive is slow, drops out or is making noise, image it first instead of browsing: Image a failing drive on Mac or Windows.

What not to do

What not to do

Don’t erase or Initialize a drive that is detected but not mounting. The files are probably still there.
Don’t keep power-cycling a drive that clicks or doesn’t spin up.
Don’t open an enclosure or “tap” or chill a drive. It makes hardware faults worse.
Don’t run repairs on a drive until the files are copied off.

Get Retrova

Free and open source for macOS 11+ and Windows 10/11. No account, no recovery limit, and it never writes to the drive you’re rescuing.

Download RetrovaFree for Mac and Windows

Questions

Why does my external hard drive not show up on my Mac?

Either the Mac can’t see the device at all (power, cable, port or hardware), or it sees it but can’t mount it (file system, format or a setting). Disk Utility with Show All Devices and diskutil list tell you which.

The drive shows in Disk Utility but not in Finder. Why?

Its volume probably isn’t mounted, or Finder is set not to show external disks. Click Mount in Disk Utility, and tick External disks in Finder settings.

My drive is not detected on any computer. Can software help?

No. If no computer lists the device, the hardware has failed. Stop powering it on and contact a data recovery lab.

Will Retrova find a drive the Mac can’t see?

No. Retrova reads drives the operating system can see as a disk. It can’t reach a device that isn’t detected.