8 solutions to fix external hard drive not mounting in macOS Mojave

Posted by Molly to Mac Data Recovery on June 12th, 2018

This article will show you 8 solutions to troubleshoot and fix the external hard drive not mounting in macOS Mojave/High Sierra error. You can also recover data from the unmountable external hard drive with iBoysoft Mac Data Recovery to avoid unexpected data loss.

Normally, when you plug in an external hard drive to Macs, you'll see it mounted on the desktop, in Finder and in Disk Utility. Then you can read, edit, copy and delete files on the mounted drive. However, if you are unable to mount external hard drives, you cannot access the data at all. Don't worry. There're 8 solutions you can follow to make the external hard drive mounted in macOS Mojave/High Sierra/Sierra.

How to fix external hard drive not mounting in macOS Mojave issue?

Solution 1: Check if the hard drive is properly plugged in.

Since the connection between your Mac and external hard drives relies on cables, loose connections often lead to external hard drives not being recognized. So make sure the connection is in good condition.

Solution 2: Check if the USB port/USB hub is unmatchable, damaged or lack of power.

If your external hard drive or flash drive is not mounted on Mac, try plugging it into another USB port or a USB hub. That's because there're USB 3.0 and USB 2.0 ports which are different. Besides, insufficient power supply or damaged USB ports could also lead to external hard drives not mounting in macOS Mojave. You can unplug a workable drive and then plug the problematic external hard drive to see if it can be mounted right.

Solution 3: Check if your Mac is set to show mounted drives on the desktop.

It's also possible that your Mac has already recognized the external hard drive but not showing up on Mac desktop. Under such circumstance, you should go to Finder > Preferences > General and make sure the "External disks" option is ticked. Then you'll see the external hard drive mounted on the desktop.

Show external disk on the desktop

You can also set your Mac to show external hard drives in Finder. Go to Finder > Preferences > Sidebar and make sure the "External disks" option under "Locations" is ticked.

Show external hard drive in Finder

Solution 4: Check if the external hard drive is Windows formatted.

Normally, Macs can only read Windows formatted NTFS drives, no writing supported. The NTFS formatted external hard drive can also show up in Disk Utility. If this is the case, you can backup the files on the NTFS drive and then format it to Mac supported file systems (APFS, HFS+ or HFS) or file systems supported by both Windows and Mac, like FAT32 and exFAT.

A better method is to install an NTFS for Mac application which enables you to read and write to NTFS drives on Mac without reformatting.

Solution 5: Check if the external hard drive is mounted in Disk Utility.

Go to Disk Utility to see if your external hard drive appears there. If the external hard drive shows up in Disk Utility but not mounted, click the Mount icon then the external hard drive will be mounted in macOS Mojave.

However, if the external hard drive appears there but unmountable or no volumes of that external drive listed, you need to fix it with First Aid to make the files accessible again.

First Aid

Solution 6: Fix the unmountable external hard drive with Terminal.

If your external hard drive can be recognized by your Mac but can't be mounted, try to disconnect it and remount via Terminal. Follow the steps carefully as below:

1. Go to Applications > Utility > Terminal.

2. Type in diskutil list. Look for the section labeled /dev/disk_ (external, physical), remember the disk number.

Terminal

3. Type in diskutil info disk_. Replace "_" with your external disk number. This is to check if your system recognizes this drive.

4. Once confirmed, type in diskutil eject disk_ to eject the external drive.

Eject drive in terminal

5. Physically remove the external drive and then re-plug it. Hopefully, your external hard drive will be mounted in macOS Mojave.

Solution 7: Check if the external hard drive is corrupted.

If unfortunately, none of the above solutions worked, it's very likely that the drive is corrupted or damaged. It could be the result of file system broken, virus attacks, improper ejection, etc. If there are no important files on the external drive, you can directly reformat it in Disk Utility.

1. Go to Applications > Utilities > Disk Utility.

2. Select the unmountable external hard drive and click "Erase" on the top.

Erase external hard drive

3. Provide the required information to format the drive.

4. When finished, you can mount the external hard drive in macOS Mojave and use it again.

Solution 8: Recover lost data and reformat the unmountable external hard drive.

If you have important files on that drive, you have to recover data from the unmountable external hard drive with reliable data recovery software, such as iBoysoft Mac Data Recovery.

iBoysoft Mac Data Recovery is able to recover data from not mounted hard drives in High Sierra, recover data from corrupted external APFS drives, recover data from unreadable external hard drives, recover deleted/lost data from APFS drives, and recover data from formatted APFS files, etc.

Step 1: Download and install iBoysoft Mac Data Recovery on macOS Mojave.

Step 2: Launch this program. Select the unmountable hard drive and click "Next". The program will start scanning this drive for lost files.

Recover data from not mounting external drive in macOS Mojave

Step 3: During or after the scanning process, you can double click the found files and preview them.

Step 4: Choose what you want to get back and click "Recover".

Step 5: Go through the recovered files and make sure all desired files are back.

Conclusion: To fix external hard drive not mounting in macOS Mojave error, you can try out the methods above one by one. If unfortunately your data lost from the unmountable external hard drive, you can recover lost data from unmountable hard drive with iBoysoft Mac Data Recovery. But more importantly, if you don't want to suffer the pain from data loss, you'd better backup your files on a regular basis.

Still have questions?