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How to Fix Unreadable USB Flash Drives on Mac without Data Loss

Updated on Friday, May 20, 2022

iBoysoft author Jessica Shee

Written by

Jessica Shee

6 Solutions to Repair USB Not Readable on Mac (2022)

Summary: This post tells you how to repair a USB not readable on Mac. You can download iBoysoft Data Recovery for Mac to get your files off the USB device first to avoid data loss.

How to repair unreadable USB drive on Mac

USB flash drives play an important role in storing and transferring files between computers. But like with other storage devices, you may find the USB not readable on Mac and sometimes showing the USB Accessories Disabled on Mac error message. In which case, you need to fix the unreadable USB flash drive on Mac and retrieve data from it.

Table of Contents:

Let's look at some of the signs that urge you to repair the USB drive on a Mac.

Signs indicating the need to repair USB not readable on Mac

USB flash drives not readable on Mac

Why is my USB not readable on Mac? False connection, no file system, unsupported disk encryption, and information corruption are all possible to make Mac USB not readable. Here are some of the signs signaling the need to repair USB on Mac:

It's hard to pinpoint the exact causes of one case, but we will troubleshoot the problem and tell you how to fix an unreadable USB flash drive on Mac effectively.

How to fix an unreadable USB flash drive on Mac?

Before getting started, we need to rule out the cable and USB port not working issues. Use another device with the cable and port you used with the unreadable USB device. If you find no problem with the cable and port, we can now focus on the drive itself.

Check the USB port or cable of unreadable USB flash drive

Check whether Disk Utility detects the USB stick. If the drive is not recognized in Disk Utility, and it doesn't work with other computers as well, it most likely has hardware problems. Given that, you should send it to a specialist for further measurement and disk repair.

Suppose Disk Utility lists your USB on the left sidebar, then you may still stand a chance to repair the USB drive on Mac yourselves. Follow the solutions below to fix USB drive not readable on Mac.

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

  1. Check if the USB device is encrypted or has no file system
  2. Update the USB driver
  3. Repair the corrupted USB drive with Disk Utility First Aid
  4. Repair external hard drive with Mac Terminal
  5. Recover files and reformat the corrupted USB drive
  6. Find a USB repair technician near you

Solution 1: Check if the USB device is encrypted or has no file system

Did you receive an error message telling you that the drive you inserted is not readable? What happens when the inserted USB drive is encrypted or not formatted(uninitialized).

If the drive was used on a Windows PC with BitLocker encryption, you can either remove the encryption in a Windows computer or use a BitLocker for Mac tool to fix the unreadable drive on Mac.

If the drive is new and has not been pre-formatted, format the uninitialized USB in Disk Utility, then you can read and write files to it.

But if your USB device is not BitLocker-encrypted and has a file format working on Mac, you likely have a corrupted drive. Please read the solutions below to fix the corrupted USB on Mac.

Solution 2: Update the USB driver

An outdated USB device driver is one of the common reasons causing a USB drive not readable on Mac. Therefore, updating the driver, which restores the normal interaction between your Mac and the USB drive, can resolve the USB issue and improve performance.

To update the USB driver, you need to update the Mac operating system. Follow these steps to check if any update is available for your Mac:

  1. Click on the Apple in the upper left corner of the screen.
  2. Select "Software Update..."

If Mac suggests a new macOS update, follow its instruction to update it, then try using the USB device again.

If your Mac is up to date, you can visit the USB manufacturer's official website to see if it offers any driver updates. Otherwise, the drive may have file system problems, move on to solution 3 to learn how to fix a USB drive when the USB is not readable on Mac due to file system error.

Solution 3: Repair USB drive on Mac with Disk Utility First Aid

When a disk experiences file system errors caused by corrupt files, disk integrity corruption, bad sectors, etc., you can't access files on it. Luckily, your computer has a built-in Mac disk repair software called Disk Utility First Aid, which you can employ to scan the corrupted flash drive and fix the damaged file system.

Here is how to repair a corrupted USB on Mac:

  1. Launch the Mac disk management tool - Disk Utility from Launchpad > Other > Disk Utility.
  2. Select the corrupted drive from the sidebar.
  3. Click First Aid at the top of the window, and then click Run.Fix unreadable USB drives with First Aid
  4. Wait until the repair process finishes.

If Disk Utility successfully repaired your thumb drive, you can now open files on the drive.

If Disk Utility First Aid failed on the external hard drive, you could repair the USB drive with Mac Terminal.

Solution 4: Repair external hard drive with Mac Terminal

Using the corespondent command in the Mac Terminal app gives you a bit more control over verifying and repairing the USB drive than running First Aid in Disk Utility.

Here is how to execute flash drive repair with Mac Terminal:

1. Open Terminal from Launchpad > Other > Terminal.

2. In the command prompt window, enter the following command to list all devices connected with your Mac.

diskutil list

3. Note down the disk identifier, such as disk 2.

Get disk identifier of the USB drive

4. In the command-line interface, enter the command below to verify the disk and press Enter.

diskutil verifyDisk /dev/disk identifier

verify the USB drive

5. If it reports any partition map or file system errors, type in the following command to repair the disk.

diskutil repairDisk /dev/disk identifier

repair the USB drive on Mac with Terminal

6. You will receive a message reminding you that "repairing the partition map might erase the disk.". It usually won't erase data on the USB device, but you can recover files that matter to you first. Type y in the command prompt then hit Enter.

Hopefully, Terminal managed to repair the corrupted USB drive, and you have regained access. If not, reformat the removable disk with Disk Utility (Disk Management on Mac).

Solution 5: Recover data and reformat the corrupted USB drive

If the removable disk has errors First Aid and Terminal cannot repair, reformatting will be the final option. Reformatting restores the USB drive to the original state on Mac by setting up a working file format. But it will also erase all data on it and thus requires data recovery beforehand.

how to avoid data loss

iBoysoft Mac Data Recovery is the best USB 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 12 Monterey/macOS 11 Big Sur/Catalina 10.15 or older to recover an unreadable flash drive. Also, it supports M1 Macs with standard M1 chips and the more advanced M1 Pro and M1 Max chips.

1. Connect the USB drive to Mac.

2. Launch iBoysoft Data Recovery for Mac.

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

Recover lost data from unreadable USB flash drive on Mac

4. Wait for the scanning process to complete.

iBoysoft Mac data recovery software

5. Preview the scanning results and choose files you want to recover, and then click the Recover button to recover data that's important to you.

Mac usb drive data recovery

Now that you have successfully recovered files, you can format the USB drive on Mac to make it readable again. Safely eject the drive and try it again if Disk Utility won't let you erase the USB drive on Mac.

If you tried all the solutions mentioned above but still can't repair the unreadable USB flash drive, you need to send the corrupted USB drive to a local technician.

Solution 6: Visit a professional repair service center

If the USB drive remains unreadable, it may have physical damage that you can't repair yourself, such as problems with the flash drive's internal storage. You can either get a new drive or find professionals to recover valuable data from the bricked USB drive and fix it.

What will render a flash drive unreadable?

Actually, USB devices are susceptible to such kinds of corruption, as these USB devices are constantly plugged in and out.

If your USB is not readable on Mac, it may have these issues:

USB flash drive is virus-infected

A virus or a Trojan may delete critical system elements, thus disabling the OS and making the USB device unrecognized.

USB flash drive file system corruption

When the USB flash drive was improperly removed from the computer due to a sudden power outage or pulled out without unmounting, it will be prone to corruption.

Faulty USB cable or port

If the USB port or flash drive cable of the computer is not working properly, your Mac computer won't recognize or read the flash drive.

Out-of-date drivers

If the device driver is out of date, it will affect the ability of the USB flash drive to communicate with the operating system, causing it to be unreadable.

Disk encryption method not supported on Mac

If a drive is mainly used on Windows, you may enable BitLocker encryption to add more security. But this extra layer can't be processed by macOS; thus, you can't assess the drive on Mac.

No file system

File systems control how data is stored and retrieved; without them, drives are inaccessible.

Physically damaged flash drives (dead/broken USB devices)

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 that can help you.

NAND memory chip renders the USB device unreadable and displays the wrong size.

How to Prevent a USB stick from being corrupted?

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

Secondly, download and install an anti-virus program to 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 to back up important files as it is the golden rule to avoid data loss.

If unfortunately, you have important data on the broken USB drive, you can rely on iBoysoft USB Data Recovery for Mac to recover data on it.


We hope you have fixed the unreadable USB flash drive, and now it's working perfectly on your Mac. Which solution helped you out? Do you have any other great solutions to fix this issue? Please don't hesitate to share them with us.

FAQ about USB not readable on Mac


The cost to perform a flash drive repair varies. If minor software issues cause it, you can use the free USB repair tools to get it fixed. In cases that data recovery is needed, a paid data recovery software costs under $90. If the (printed circuit board) PSB or solder pads are physically damaged, it will cost you hundreds of dollars to repair and recover data from the drive.


Yes, USB drives can be repaired. You should follow the instructions in this post to fix the USB not readable issue first. If the USB drive is still not working, seek help from a professional USB repair center.