How to fix external drive not mounting on Mac issue without data loss?

By Juno | Posted to Mac Data Recovery, updated on August 28th, 2019 |

Summary: If your external drive is not mounted on Mac, you can't access data stored on it. Here is how to fix external drives, including external hard drives, SD cards and USB flash drives, etc., not mounting on Mac issue without data loss. You can also download iBoysoft Mac Data Recovery to recover data from unmountable external drives first.

Usually, an external drive will be mounted automatically on your Mac once you plug it in, and you can access data on this drive. However, this time, your external hard drive is not mounting or recognized by your Mac. It's annoying when you find that you are unable to mount external hard drive on Mac, just like the user below.

"I have a 500 GB older HP external drive, formatted as macOS Extend journaled on MacBook Pro 2014 and I have been using it to do Time Machine backups. Now after updating to macOS Mojave, this external drive just won't mount. The main drive shows in Disk Utility but the backup partition is not showing up. I can't do First Aid as it doesn't show up. Any ideas? Thanks! I need help to recover my important files from this unmountable external drive."

So, this article will give you some information about why your external drives won't mount on your Mac, as well as teach you how to fix this disk problem as this table shows.

Table of contents
1.Why an external drive is not mounting on Mac?
2. Basic suggestions on external drive not mounting problem
3. How to fix external drives not mounting on Mac issue without data loss?

Tips for fixing external drive not mounting issue

Before you go further, there are some tips that deserve your attention. When your disk become unmountable on Mac, you should not go straight to reformat this external drive, especially when you have important files on it. This is because reformatting will wipe the data on this drive and cause serious data loss if you don't have a copy of a data backup.

On the contrary, you should stop using this external drive right away. The reason for such cautiousness is that any further operation is very likely to overwrite your original files and make them irrecoverable.

Key takeaway:

  • Do not format this external drive before you get your data back.
  • Do not save new things to this drive, or perform other operations like deletion, file removal, etc.

Now, let's go into details about the external drives not mounting on Mac issue.

Fix external drive not mounting on Mac issue without data loss

Why an external drive is not mounting on Mac?

You probably go crazy because you don't know why this external drive is not mounting on Mac. As a matter of fact, this problem could be caused by many factors, such as damaged file system, virus attack, unsafe ejection or any other improper operations.

Here are some common ones.

  1. A damaged file system: If your external drive is attacked by virus or if you abruptly eject this drive, it's likely that the file system of this disk would be damaged or corrupted. As a result, the operating system is unable to recognize this disk, and the disk will not be mounted or read by macOS.
  2. Connection problems: Another reason that your external drives is not mounting on Mac could be a dirty or loose connection between your cable, USB-C multi-adapter, Thunderbolt 3,  or other connecting ports. A clear, clean, snug and fit tightly connection is the premise of mounting an external drive successfully.
  3. Hardware issue: Also, problems related to hardware could also make the disk unmountable, especially when your external drive has too much bad sectors or have been physically damaged.

But no matter what the reason is, the first and most important thing for you probably is to fix this disk problem.

Basic suggestions on external drive not mounting problem

In case you miss anything necessary, you can also have some basic checks as following when you are unable to mount an external hard drive on your Mac computer.

1. Re-plug your external drive to another port or try another USB cable. A faulty connection, though it is foolproof, is often the key to fix the external drive not mounting issue, in that users always forget to check if the port is wobbly or if the cable is broken.

2. Try a super slow jam. Strange but true, some users found that their external will mount properly when they plug it in exceptional slow motion. However, if they try and plug in the external drive normally, the Mac don't recognize the disk.

3. Check your Finder Preferences. When your external drive is not mounting on the desktop, you can open Finder, choose "Preference" (or press Control +, ) and check "External disks" both in General tab and in Sidebar tab to show your external drive on your Mac computer.

How to fix external drives not mounting on Mac issue without data loss?

After knowing what possibly makes your external drive unmountable, you can set out to fix this issue on your Mac. There are three solutions suggested in this part, and you can try them one by one to troubleshoot this disk problem without data loss.

Solution 1:Manually mount this external drive in Disk Utility

If your external hard drive is not mounted on the desktop or in the Finder, you can try to mount it manually in Disk Utility which is a native disk management tool in your Mac. This is one of the easiest solutions, so you can have a bash.

1. Click Go at the upper left of your desktop and go to Utilities, then launch Disk Utility on your Mac computer.

2. Click on "Show All Devices" in View option to list or connected drives.

3. Choose the unmountable external drive in the left sidebar.

3. Select Mount in the top center of Disk Utility.

However, if you find that your external drive is not even showing up in the Disk Utility, it is very likely that your disk is suffering some physical damage. In this case, you need to send it to a local data recovery service. But if the Mount option is grayed out but you can see this external drive in Disk Utility, you can try another solution then.

Solution 2:Repair this unmountable external drive with First Aid

The second suggestion is First Aid in Disk Utility. First Aid is a very simple tool that is built in your Mac, and it is able to detect and repair directory damage and other disk errors. You are advised to run the tool more than once to ensure you are receiving a consistent result. Follow the instructions and you can correct various disk-related errors via this useful software.

1. Go to Utilities and launch Disk Utility on your Mac computer.

2. Select the unmountable external drive on the left sidebar.

3. Select First Aid in the top center and click Run.

Repair this unmountable external drive with First Aid

Solution 3:Fix the external drive not mounting issue by reformatting

If your external drive still can't be mounted in Disk Utility after you perform First Aid or First Aid failed to repair it, your drive should have some serious errors like file system corruption.

Disk Utility failed to repair external drive

Under this circumstance, many Mac-noobs would choose to search on Google for solutions when Disk Utility can't repair this disk. Most of you are told to reformat this drive. However, it's not a good idea for people who have important files on this drive. It could be precious family photos, valuable work documents, or any other files.

Instead, if you don't have a copy of a data backup in hand, using this step-by-step guide to recover data from this unmountable external drive is better than format it directly.

How to recover data from unmountable external drives on Mac?

As long as your external drive doesn't have any hardware problem, fortunately, you can retrieve your files with professional Mac data recovery software - iBoysoft Mac Data Recovery with no fuss.

Best External Drive Data Recovery - iBoysoft Mac Data Recovery

  • Recover data from unmountable, formatted, inaccessible, unreadable, corrupted external hard drives.
  • Supported storage devices: external hard drives, USB flash drives, memory cards, SD cards, etc.
  • Supported file types: photos, videos, audio files, documents, emails, etc.
  • Suppported Mac OS: macOS 10.15/1.14/10.13/10.12 and Mac OS X 10.11/10.10/10.9/10.8/10.7.

Read-only & risk-free

Tutorial for external drive data recovery on Mac with iBoysoft Mac Data Recovery

1. Free download and install iBoysoft Mac Data Recovery on Mac.

2. Launch iBoysoft Mac Data Recovery.

Recover data from not mounting external drive on Mac with iBoysoft Mac Data Recovery

3. Select the external drive that is not mounting and click "Next" button to scan for all lost data.

4. Preview the searching results, choose files you need, and click "Recover" to get them back.

Preview and Recover data from not mounting external drive on Mac with iBoysoft Mac Data Recovery

Note: You need to save the recovered files to another usable drive. By this means, you will not lose them again when you move forward to the steps to fix not mounted external drives in the following part.

5. Have a check to ensure you have got all lost data back.

After having successfully restored all data on this drive, you can set out to erase this external drive to fix the disk not mounting on Mac issue.

Tutorial to reformat unmountable external drives on Mac

1. Launch Disk Utility.

2. Click the icon of your unmountable external drive on the left sidebar.

3. Click on the Erase button function on the top of the Disk Utility window.

Repair this unmountable external drive with by reformatting

4. Complete the related information (name, format, scheme), then click Erase button to finish reformatting.

Erase disk to fix unmountable external drive on Mac

After reformatting, your external hard drive will be assigned with a new file system. And you can go ahead to mount this drive on your Mac normally.

Conclusion:

If your external drive like a hard drive, an SD card, a USB flash drive, etc. is not mounting on your Mac, don't be panic. Most of the time, you are going to fix this disk problem with the solutions above. Moreover, if you worry about data loss when the disk becomes unmountable, you can use iBoysoft Mac Data Recovery to recover your files first. Remember that, no matter what disk problem you meet, you should perform hard drive data recovery before reformatting the problematic drive.

Juno

Juno is a technical expert @iBoysoft. She has over 5-year experience in data recovery/repair technology. She loves to write data recovery tips and tutorials.

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