How to fix external hard drive was not readable on macOS Mojave without losing data?

Jessica | Posted to Mac Data Recovery, updated on June 4th, 2019 |

Summary: The external hard drive you inserted was unreasable? This article will teach you how to make the external hard drive readable on your Mac again without losing any data with iBoysoft Mac Data Recovery.

If an external hard drive becomes unreadable after updating to macOS Mojave, you need to firstly verify whether that's the problem of the external hard drive.

It's very simple:

Plug in a different external hard drive or USB drive to Mac, if this new external hard drive is readable on macOS Mojave, then it's the problem of the external hard drive.

This article will show you why the external hard drive is not readable on macOS Mojave, and also how to fix the unreadable external hard drive on macOS Mojave.

Quick navigation
1. Why the external hard drive was not readable on macOS Mojave?
2. How to fix the unreadable external hard drive on Mac?
3. Methods to protect external hard drives from being unreadable

Why the external hard drive was not readable on macOS Mojave?

Firstly, let's take a look at a thread from Apple Community.

I have a Seagate 500GB external drive with photos and beloved movies. Everything was working fine until I plugged it onto the newly updated MacBook macOS Mojave. I was told that the external drive is not readable. So, why is my Seagate external hard drive unreadable on macOS Mojave? How can I recover data from the unreadable external drive?

--from Apple Community

external hard drive was unreadable on Mac

"The disk you inserted was not readable by this computer" error may happen to external hard drives, USB drives, SD cards, memory cards, CF cards and other external storage devices. Directory corruption of the drives could be the cause. There're various reasons, like:

1. Catalog files damaged

Catalog files on external hard drive contain records for all files and directories. Their main functionality is to determine how the operating system can access data. If they are corrupted, the operating system is not able to read the stored data.

2. File system errors

The information stored on external hard drive about the file system is corrupted or unreadable. The operating system can't recognize what file system the external hard drive is formatted with.

3. Sudden power off

Unexpected power off is a common cause for data loss or corrupted drives especially during heavy data transferring or writing.

4. Improper operation

Instead of ejecting the external hard drive safely first, many of people tend to pull the external hard drive out violently.

5. Force restart

A lot of people like to force restart their computer whenever software is not responding even with external hard drive plugged in. This move will probably damage the external hard drive.

6. Virus or malware attacks

Many people download malware onto their computer or external hard drive without awareness. Malware and virus can cause damage to the external hard drive and make it unreadable.

the disk you inserted in was not readable

Warning: You will see three options: initialize, Igonore and Eject. Before you recover the data on the external hard drive, do not click Initialize. Click Ignore.

No matter what the cause is, you'll have no access to the external hard drive as well as the data stored on it.

In order to fix the external hard drive not readable on macOS Mojave issue and recover data from the unreadable external hard drive, there're five effective solutions.

How to fix the unreadable external hard drive on macOS Mojave?

causes and slolutions for unreadable external hard drives

Solution 1: Change the USB cable and/or the USB port

Physical damage of a USB cable or USB port happens a lot. It will result in unreadable external hard drives on Mac. Many a times changing a USB cable or plugging the external hard drive to another USB port can solve the problem easily.

Solution 2: Check if the external hard drive is encrypted

An encrypted APFS external hard drive can be read on Mac, but an external hard drive which is encrypted by a third-party software is not readable on Mac. You will have to use the corresponding software to open it.

For example, if the unreadable external hard drive is encrypted by BitLocker, you need to find corresponding software to decrypted it first, and then access to your videos and other files.

Solution 3: Update or reinstall the driver

An out-of-date driver on your mac will cause the external hard drive unreadable. Please follow the guide to see if any update is available:

  1. Step 1: Click on the Apple icon at the upper left corner of the screen.
  2. Step 2: Select System Preference and click on Software Update.
  3. Step 3: Any updates available will be listed and you can select Update All to update all pending updates.
  4. Step 4: Wait for updates to complete and the try you re-plug in your external hard drive.

Solution 4: Fix the unreadable external hard drive with First Aid

Disk Utility's First Aid is a built-in tool on Mac to check and repair file system errors. First Aid is able to verify and fix minor problems if an external device doesn't work properly.

  1. Step 1: Go to Applications > Utilities > Disk Utility.
  2. Step 2: Select the unreadable external hard drive from the side bar.
  3. Step 3: Click First Aid.

If First Aid failed on external hard drives, you have to move to the next solution and recover file from the unreadable external hard drive before initializing it.

Solution 5: Recover data from the unreadable external hard drive and initialize it

Before clicking Initialize, please make sure you have a backup copy of the files. Otherwise, you need to at first recover data from the unreadable external hard drive with data recovery software, like iBoysoft Mac Data Recovery.

iBoysoft Mac Data Recovery is one of the best macOS unreadable external hard drive recovery software. It is able to recover data from unreadable external hard drives, recover data from unreadable USB flash drives, recover data from unreadable SD cards, recover data from corrupted external hard drives, recover data from unmountable, formatted, deleted or lost partitions, etc.

External hard drive data recovery software - iBoysoft Data Recovery for Mac

  • Recover data from corrupted/unmounted/unreadable drives.
  • Recover data due to system crash.
  • Recover videos, photos, documents, music, etc.
  • Support APFS, encrypted APFS, HFS+, exFAT and FAT 32 file system.
  • Support macOS 10.14/10.13/10.12 and OS X 10.11/10.10/10.9/10.8/10.7.

Read-only & risk-free

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

iBoysoft data Recovery for Mac

Step 2: Launch this program. Select the unreadable external hard drive and click Next. The program will start scanning this drive for recoverable files.

iBoysoft data Recovery for Mac

Step 3: After the scanning process finishes, you can click the found files to preview.

iBoysoft data Recovery for Mac

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

Note: Remember to go through all files to make sure all of desired files are recovered. If not, click Deep scan to restart the scanning for more files.

After recovering data from the unreadable external hard drive with iBoysoft Mac Data Recovery, you can now go to Disk Utility to erase the external hard drive and re-use it again.

Here is how exactly to reformat the unreadable external hard drive:

  1. Step 1: Go to Applications > Utilities > Disk Utility.
  2. Step 2: Select the unreadable external hard drive from the side bar.
  3. Step 3: Click Erase.
  4. Step 4: Type in Name and choose a format for your external hard drive.
  5. Step 4: Click Erase button.

Tips: If you want your external hard drive to be compatible with both Mac and Windows, formatting it with exFAT is recommended. If you use your external hard drive on Mac, you can choose to format it with APFS/ APFS (Encrypted)/APFS (Case-sensitive)/ APFS (Case-sensitive, Encrypted).

After the reformatting process is completed, the unreadable external hard drive should be working.

Methods to protect external drives from being unreadable

It is very common that the external drive you inserted in mac is not readable, which can result in severe data loss. In order to avoid the bad situation, some precautions you can take as follows:

1. Back up. Back up. Back up.

If you like to store your important files onto an external hard drive, always remember to save a copy of your files onto another storage device such as USB flash drives, SD cards, etc. What about losing data from an SD card? Please refer to how to recover data from SD cards.

2. Safely eject external hard drive.

Violently pulling out the external hard drive is a common cause for unreadable external disk issue. External hard drives can be corrupted if you turn off your computer without properly ejecting external hard drive too. It only take you two seconds to right-click the external hard drive and hit Eject.

3. Use advanced file system such as APFS, HFS+, and exFAT on Mac.

Advanced file system is more stable and secure.

4. Avoid physical damage.

Take good care of your external hard drive to avoid physical damage to its USB cable, USB port or storage sectors.

Jessica

Jessica, a data recovery expert @iBoysoft, loves to share free and useful data recovery solutions with people to help them get their important files back on Windows and Mac.

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