6 solutions to repair/fix unreadable/corrupted USB flash drives on Mac computers

Posted by Autumn X to Mac Data Recovery on July 18th, 2017

It is terrible when you plugged in a USB flash drive to your Mac computer but got the error "The disk you inserted was not readable by this computer". Once the USB flash drive becomes unreadable/corrupted, you will be unable to access the data stored on it. Relax. This tutorial will show you how to repair/fix unreadable/corrupted USB flash drives on Mac and also recover lost data from the unreadable USB flash drive with iBoysoft Mac Data Recovery, according to your situation.

Table of contents
1. Problem - USB flash drives not readable on Mac
2. Why is USB flash drive is not readableon Mac?
3. How to fix/repair the unreadable/corrupted USB flash drive on Mac?
4. Bonus tips
5. Conclusion

Problem - USB flash drives not readable on Mac

A USB flash drive or other removable data storage medium is widely used for storing and transferring data from an iMac, MacBook or Mac Mini. Generally, when you insert in a USB flash drive, it will be mounted in Disk Utility and on Desktop. Then you can read and write to the USB drive.

However, what a very distressing situation if your USB flash drive is not readable/recognizing/working/showing up on Mac, especially when you desperately need to access some data stored on it. A Mac user has reported this issue in forum:

"I have a 32 GB USB which has suddenly come up with a message stating the USB flash drive is not readable by this computer (Apple MacBook Pro). I do not want to initialize it as this will result in loss of my data. How can I fix the unreadable USB on Mac and recover lost data?"

Why is USB flash drive is not readable on Mac?

Actually, USB drives are susceptible to such kind of corruptions, as these drives are usually connected to any system. Here are some of the common reasons behind this issue:

  • > Severe virus infection to your USB flash drive. A virus or a Trojan may delete critical system elements, thus disabling the OS and making the drive unrecognized.
  • > Sudden power surge or abrupt removal of USB flash drive. The flash drive was removed improperly from the computer which led to the corruption of its partitions.
  • > Faulty USB port or cable. If the USB port or cable of the computer is not working properly, your Mac computer won't recognize or read the flash drive.
  • > Incompatibility issues between the file systems of both flash drive and the Mac computer. In case the USB flash drive is formatted with the NTFS file system which isn't compatible with macOS.
  • > Out-of-date drivers. If drivers are out of date, the Mac operating system and your applications on the computer will fail to interact with all hardware devices. So the USB flash drive becomes unreadable.
  • > The USB drive is physically damaged. If your USB drive is seriously broken by hitting, dropping, shaking, etc., there is no USB repair tool or USB flash recovery software for Mac can help you.

How to fix/repair the unreadable/corrupted USB flash drive on Mac?

Solution 1: Check the USB port or cable

Check that USB port on your Mac. Plug into a different USB port or plug another device in and see if that works OK. Also, make sure that it's not faulty. Try using a different USB cable with the USB drive to see if that fixes the non-readable problem.

Solution 2: Update or reinstall the driver

When you are having problems with a device, you should check if any updates are available please do the following:

Step 1: Click on the Apple in the upper left corner of the screen.

Step 2: Select "Software Update..."

Step 3: Any updates available will be listed and able to be downloaded or you will be told your software is up to date.

Solution 3: Check the file system format

If the files system is NTFS format, it's not hard to understand why the USB flash drive is unreadable on Mac. To make sure, you can go to Disk Utility and check its file system. To fix the incompatible issue, you can download and install an NTFS driver to read and write NTFS drives on Mac.

Solution 4: Fix the unreadable USB flash drive with First Aid

Disk Utility's First Aid is capable of repairing minor errors of disks, such as fixing a USB flash drive that is not readable/recognizing/working/showing up on Mac.

Step 1: Launch Disk Utility from Utilities.

Step 2: Select the unreadable USB drive from the sidebar.

Step 3: Click First Aid at the top of the window, and then wait until the reparation process finishes.

Fix unreadable USB drives with First Aid

Solution 5: Reformat the unreadable USB drive

If First Aid failed to fix the unreadable drive, it indicates that the USB drive might have severe errors beyond its capability. Then the best solution is to reformat the unreadable USB drive and make it readable or usable again. This process will wipe all data stored on the USB drive. So, please make sure you have a backup copy, or, follow the steps to recover lost data from the unreadable USB drive with iBoysoft Mac Data Recovery.

iBoysoft Mac Data Recovery is a free USB drive data recovery tool that supports recovering deleted videos, documents, photos, music and much more files from unreadable USB flash drives, Mac hard drives, external hard drives, SD cards, memory cards and other storage devices macOS Catalina 10.15/Mojave 10.14/High Sierra 10.13/Sierra 10.12 and Mac OS X 10.11/10.10/10.9/10.8/10.7.

Besides, iBoysoft Mac Data Recovery also recovers deleted files from flash drives, recover lost data from formatted, inaccessible, unmounted, corrupted drives. It

Steps to recover lost data and fix the unreadable USB drive on Mac

Step 1: Connect the unreadable USB drive to Mac.

Step 2: Launch iBoysoft Mac Data Recovery.

Recover lost data from unreadable USB flash drive on Mac

Step 3: Select the unreadable USB and click the Next button. The program will start to scan for lost files.

Step 4: Preview the scanning results and choose files you want to recover, and then click Recover button to get those files back.

Step 5: Launch Disk Utility from Utilities and select the unreadable USB drive.

Step 6: Click Erase on the top of the window, and follow the on-screen instructions to reformat the unreadable USB drive.

Hopefully, the USB drive will be readable now.

Solution 6: Send the unreadable USB drive to a local technician

Sometimes, the unreadable USB drive can't be fixed by reformatting. In this case, the unreadable USB drive is probably damaged physically, and you have to ask a local technician for help.

Bonus tips: Firstly, make sure that your USB flash drives don't become unreadable/corrupted in the future by always properly unmounting the disk properly after using it.

Secondly, download install an anti-virus program and check your computer and USB drive for virus or malware regularly.

Moreover, keep the driver and the Mac computer updated. The last and most important thing is to remember backing up important files as it is the golden rules to avoid data loss.

If unfortunately, you have lost data on your Mac computer or any other storage media, you can rely on iBoysoft Mac Data Recovery. Just download this program and get all lost data back.


Wish you have fixed/repaired unreadable/corrupted USB on Mac with these solutions above. These effective solutions also can be used to fix USB not recognizing/working/showing up on Mac.

Which solution really helps you out? Do you have any other great solution to fix this issue? Please don't be hesitate to share them with us.

Still have questions?