6 Solutions to Repair Unreadable/corrupted USB Flash Drives on Mac

By Jessica | Posted to Home > Mac Data Recovery Tips, updated on January 12th, 2021

Summary: It tells you the reasons and solutions for the USB that is not readable on Mac. To avoid data loss, you’d better recover data from the unreadable flash drive with iBoysoft Data Recovery for Mac before you fix it.

How to repair unreadable USB drive on Mac

Problem Description - USB flash drives not readable on Mac

USB flash drives not readable on Mac

As we all know, USB flash drives are widely used for storing and transferring data from an iMac, MacBook or Mac Mini, though newer MacBook Pro and Air uses no USB 3.0 port.

"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?"

Generally, when you insert in the USB pen drive, it will be mounted in Disk Utility and on Desktop for data access. However, a very distressing situation happens, just as the user above, is that the USB is not readable on Mac.

How to fix unreadable USB flash drive on Mac?

Here are 6 methods to fix your unreadable USB thumb drive and make it working on your Apple Mac again.

Solution 1: Check the USB port or cable

Check the USB port or cable of unreadable USB flash drive

Check that USB port on your Mac. Plug into a different USB port or plug another device in and see if that works OK.

If you use a USB hub bacause your MacBook has no USB 3.0 port, also make sure the hub is 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 your USB flash drive is not readable by your Mac, especially after a recent macOS Big Sur update or you haven't updated the macOS for years, you should check if any updates are available please do the following:

  • 1. Click on the Apple in the upper left corner of the screen.
  • 2. Select "Software Update..."
  • 3. Any updates available will be listed and able to be downloaded or you will be told your software is up to date.

If not, check the official website of the USB manufacturer for any update.

Solution 3: Check the file system of the USB drive

If the files system is NTFS, 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: Repair the unreadable USB flash drive with First Aid

You don't have seek for online USB flash drive repair. Instead, Disk Utility's First Aid on your Mac is capable of repairing minor errors of disks.

Here is how to repair USB flash drive when it's not readable, not recognized, not working, or even not showing up on your Mac.

  • 1. Launch Disk Utility from Utilities.
  • 2. Select the unreadable USB drive from the sidebar.
  • 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: Recover and 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 format the USB drive on Mac and make it readable or usable again. But formatting a drive will wipe all data stored on it. So, you'd better get files off the unreadable USB with a data recovery tool.

Recover unreadable USB drives to avoid data loss

iBoysoft Mac Data Recovery is a free USB drive data recovery software that supports recovering lost files from unreadable USB flash drives from Samsung, SanDisk, Toshiba, Lexar, PNY, etc.

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

Now, download iBoysoft Data Recovery for Mac on your macOS Big Sur 11/Catalina 10.15 or older to recover unreadable flash drive.

  • 1. Connect the unreadable USB drive to Mac.
  • 2. Launch iBoysoft Data Recovery for Mac.
  • Recover lost data from unreadable USB flash drive on Mac
  • 3. Select the unreadable USB and click the Next button. The program will start to scan for lost files.
  • 4. Preview the scanning results and choose files you want to recover, and then click Recover button to get those files back.

Then, you can format your USB drive to make it readable on your Mac again.

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

Sometimes, the unreadable USB drive is bricked and can't be fixed with the above issues. In this case, this USB flash drive is probably damaged physically, and you have to ask a local repair technician for help.

Bonus tips: How to maintain an USB flash drive for usage

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 Data Recovery for Mac. Just download this program and get all lost data back.

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 plugged in and out.

Here are some of the common reasons behind this issue:

  • USB flash drive is virus infected
  • A virus or a Trojan may delete critical system elements, thus disabling the OS and making the drive unrecognized.
  • USB flash drive file system corruption
  • The USB flash drive was removed improperly from the computer for reasons like sudden power surge, abrupt removal, and unintentional touch, which leads to file system corruption.
  • 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.
  • File system incompatibility
  • The issues between the USB drive file system and macOS, for example, Windows NTFS file system is not completely compatible with macOS.
  • Sometimes, you can't even read files or folders on NTFS USB drives through an Apple M1 Mac.
  • 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.
  • A dead/bricked USB drive after physical damage
  • 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.


Wish you have fixed the unreadable USB flash drive and now it's working perfectly on your Mac. These effective solutions also can be used when USB not recognized, 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.