External Drive Won't Mount in macOS

Use these terminal commands to force mount your external hard drive or flash drive for "Could not mount…" disk errors in macOS. Often solves "mount failed with 72" and "mount failed with 71" errors as well.

1. Run this command to locate the drive you want to mount. Note it's [file system] and [disk number]:
diskutil list

2. Create a mount point (enter your Mac's admin password):
sudo mkdir /Volumes/mount

3. Run this command w/info from step 1:
sudo mount -t [file system] /dev/disk[disk number] /Volumes/mount

NOTE: "[file system]" and "disk[disk number]" should be replaced with the exact name of the drive you want to mount from step 1.

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USE THESE MOUNT COMMANDS BASED ON YOUR FILE SYSTEM
sudo mount -t ntfs /dev/disk[disk number] /Volumes/mount
sudo mount -t apfs /dev/disk[disk number] /Volumes/mount
sudo mount -t exfat /dev/disk[disk number] /Volumes/mount
sudo mount -t hfs+ /dev/disk[disk number] /Volumes/mount
sudo mount -t hfsplus /dev/disk[disk number] /Volumes/mount
sudo mount -t fat32 /dev/disk[disk number] /Volumes/mount
sudo mount -t NFS /dev/disk[disk number] /Volumes/mount
sudo mount -t Btrfs /dev/disk[disk number] /Volumes/mount
sudo mount -t XFS /dev/disk[disk number] /Volumes/mount
sudo mount -t ext2 /dev/disk[disk number] /Volumes/mount

ALTERNATE MOUNT COMMANDS:
sudo diskutil mount disk[disk number]
sudo diskutil mount /dev/disk[disk number]
sudo diskutil mount force /dev/disk[disk number]
sudo mount -t [fileSystem] -o force,rw /dev/disk[disk number] /Volumes/mount
sudo mount -t /dev/disk[disk number]

OTHER HELPFUL COMMANDS:
diskutil verifyDisk /dev/disk[disk number]
diskutil repairDisk /dev/disk[disk number]
CHECK FOR DISK ISSUES:
sudo fsck_[file system] -f /dev/disk[disk number]
GRANT READ/WRITE PERMISSION:
sudo chmod 600 /dev/disk[disk number]

BACKUP TO AN OFFSITE SOLUTION SUCH AS BACKBLAZE:
https://secure.backblaze.com/r/05lue6

UNMOUNT HARD DRIVE BEFORE UNPLUGGING
Sometimes forcing a drive to unmount is required and it's important to eject or unmount external drives BEFORE physically unplugging them to avoid potential data loss or damage. You can right-click to Eject a drive OR drag and drop the drive's icon onto the trash in macOS. This command will unmount the drive.
diskutil unmount /dev/disk[disk number]
diskutil unmount /Volumes/mount (replace mount with your location)

HOW TO FIND DISK NUMBER & FILE SYSTEM IN SYSTEM INFORMATION:
If your disk is plugged into a USB hub/dongle, your device info may appear in "Storage" in the left nav of About this Mac… More Info… System Report… Storage. You will see FileSystem and BSD Name at the top - use both in the Terminal Commands to mount the disk. BSD Name = disk[disk number]. Alternately, your disk information may appear in Thunderbolt/USB4 or USB, or Card Reader if it is a Compact Flash card.


THIRD-PARTY HFS+ FILE SYSTEM SOLUTION
You may need to install a third-party hfsplus filesystem driver. One popular option is the "osxfuse" package, which includes a hfsplus filesystem driver. Note that you'll need to have Homebrew installed to use the "brew" command. You can install Homebrew by following the instructions at https://brew.sh/.

Terminal Command:
brew install osxfuse
sudo mkdir /Volumes/mount
sudo /usr/local/bin/mount -t hfsplus /dev/disk[number] /Volumes/mount

WHEN ALL ELSE FAILS:
If your disk is unreachable, which is very rare, these commands are a LAST RESORT and will ERASE ALL DATA on the drive and reformat it in the file system you command:

sudo diskutil eraseDisk [fileSystem] "[name your disk]" /dev/disk[number]
• replace [fileSystem] with your preference.
• replace [name your disk] with the name you want to assign to your disk
• replace [number] with the number supplied by System Report or diskutil list command

sudo diskutil eraseDisk apfs "[name your disk]" /dev/disk[number]
sudo diskutil eraseDisk hfsplus "[name your disk]" /dev/disk[number]
sudo diskutil eraseDisk exfat "[name your disk]" /dev/disk[number]

——————————
Video Chapters:
——————————
00:00 The Problem
00:30 Step 1: Open System Report
01:17 Step 2: User Terminal to Make a Directory
02:04 Step 3: User Terminal Force Mount the Drive
02:50 Success: Compact Flash Card Mounts
03:08 Repeat for External Hard Drive
04:13 Wrapping Up

ANNOTATION
March 12, 2024
- updated useful commands, simplified steps
July 28, 2023
- Additional ways to get disk info in pinned comment
July 15, 2023
- added unmount info
April 05, 2023
- alternate way to find disk info in system report - storage
- added chapters
March 28, 2023
- 3rd party file systems with Homebrew
February 27, 2023
- added new commands for finding disk info
January 31, 2023
- added erase commands
January 13, 2023
- added other file systems
- added mount failed with 72 and 71 tags