4 Proven Ways to Fix The Disk You Attached Was Not Readable by This Computer

Learn the four ways below to fix the disk you inserted that was not readable by this computer on Mac. Try them individually to access your external hard drive, SD card, USB flash drive, or Android devices. If you have data loss problems, download EaseUS Mac data recovery software to get help.

Table of Contents

When Mac warns you, "the disk you inserted was not readable by this computer", it means that your external hard drive or USB flash drive has a detection issue. You may follow the quick guide here to fix this issue:

Workable Solutions Step-by-step Troubleshooting
1. Check Mac System Connect another external USB to your Mac, and check if it appears in Finder...Full steps
2. Check the File System Check if the file system of your external device is NTFS. If yes, change it to FAT32...Full steps
3. Repair with Disk Utility Connect the external device to Mac > Go to "Utilities" > Select the device and click "First Aid"...Full steps
4. Initialize Disk Open Disk Utility > Choose the problematic disk and click "First Aid" > "Repair disk" > "Erase"...Full steps

The Disk You Inserted Was Not Readable by This Computer on Mac

"My Sandisk USB flash drive becomes unreadable and inaccessible for unknown reasons. Whenever I plugged it into my MacBook, I get the error message 'the disk you inserted was not readable by this computer.' I have many family pictures and working documents saved on the USB. Is there any way to fix the flash drive and get access to my data?"

the disk you inserted was not readable by this computer

You receive the error - the disk you attached was not readable by this computer on Mac when you connect an external hard drive, USB drive, or SD card to your Mac. Many reasons could result in this error. Here is the list of the common reasons.

  • Damaged file system
  • Catalog file corruption
  • Accidental virus attack
  • Improper ejection of the device
  • Uninitialized external devices...

Fix The Disk You Inserted Was Not Readable by This Computer

Now that you have learned about the causes, you can try the solutions below to fix "the disk you attached was not readable by this computer".

  1. #1. Plug in Different Devices to Mac
  2. #2. Check the File System of Inserted Disk
  3. #3. Repair Unreadble Disk with Disk Utility
  4. #4. Initialize the Unreadable Disk

To open removable storage devices like an external hard drive, SD card, USB flash drive, or even an Android phone or tablet, you usually have to insert it into a Windows computer or Mac. But if the system files or the disk is corrupted, error messages will pop up and prevent you access the device and data. In Mac OS X, the error message usually reads, 'the disk you inserted was not readable by this computer.' 

Like what happened in the story mentioned above, many Mac users have a similar experience of this issue and want to find a fix. Here, our advice about how to solve this problem is as follows:

Solution 1. Check the Mac System to See If It Fix the Error

Just plug in a different external hard drive to Mac. If it appears on Finder, it suggests that the problem is related to the external USB devices, not the Mac. 

Solution 2. Check the File System of the Device to Fix the Unreadable Disk

Check the file system format of the external hard drive, SD card, USB flash drive, or other devices. If it is formatted with the NTFS format, it is not hard to understand why it is unreadable on Mac. To correct it, please format USB to fat32 on Mac.

Step 1. Connect the USB flash drive to your Mac computer.

Step 2. Go to "Applications > Utilities", and open "Disk Utility".

Step 3. Select your USB flash drive on the sidebar, and choose "Erase".

Step 4. Rename the USB flash drive (optional).

Step 5. Choose the format as MS-DOS (FAT) for Format, Master Boot Record for Scheme. Then click "Erase".

convert USB to FAT32 on Mac

Disk formatting will erase data for good. It's good to back up the disk in question on Mac in advance with EaseUS Todo Backup for Mac.

Solution 3. Repair the Unreadable Disk with Disk Utility (First-Aid)

Another way to fix "the disk you attached was not readable by this computer on Mac" is to run First-Aid in Disk Utility. Follow the steps below to fix the disk on Mac.

Step 1. Choose "Go" > "Utilities".

Step 2. Double-click "Disk Utility".

Step 3. Select the volume in the left pane where you want to repair permissions.

Step 4. Click the "First Aid" tab.

fix the disk you inserted was not readable by this computer on Mac with first aid

Step 5. Select the volume to which you want to install the Adobe application, and click "Run" to repair the disk.

Solution 4. Initialize the Disk to Fix The Disk You Inserted Was Not Readable

If the problem continues, you have no choice but agree to initialize the disk you inserted, as the pop-up warns. Care about important data? Download and install EaseUS Mac data recovery software on your Mac because this fix will bring data loss to the storage device.

The overall troubleshooting steps are as follows:

Step 1. Click on the "Initialize" button.

Step 2. This will open Disk Utility. From the menu bar, click "View" > "Show All Devices". You can locate the problematic drive there, which Mac recognizes it as an unformatted space.

repair the disk you inserted was not readable by this computer on Mac with Disk Utility

Step 3. Choose the drive from the left pane and click "Frist Aid".

Step 4. Click "Repair Disk". Wait until the repair process ends. Can't repair disk because Disk Utility can't repair this disk? Please continue.

Step 5. Navigate to the "Erase" button. Name the drive, select "File Format", and click "Erase". This will format your drive with the correct file system.

After this, your Mac should now recognize the disk correctly. You will no longer receive such an unreadable disk error. If you still need help, watch this video to fix "the disk you attached was not readable by this computer" on Mac.

  • 0:10 About this disk you attached was not readable by this computer error
  • 1:00 Format the external devices in Disk Utility
  • 4:34 Drag the files to the device

How to Recover Data from Unreadable Disk on Mac

To recover formatted data on the disk, open EaseUS Data Recovery Wizard for Mac and restore the USB drive to its original state on Mac. EaseUS Data Recovery Wizard for Mac is an effective tool to recover data from your USB drive, SD card, external hard drive, and more. It has many highlights:

Download this data recovery software and recover data from the unreadable external disk.

Step 1. Search for lost files

Correctly connect your external hard drive to your Mac. Launch EaseUS Data Recovery Wizard for Mac, and select the external hard drive. Then, click "Search for lost files" to find lost/deleted files on your external devices.

select the external hard drive and click Search for lost files

Step 2. Filter and find lost files

After the scan, all file types will be presented in the left panel. Select the file type to find wanted files on your external devices.

scan for lost files on external hard drives

Step 3. Preview and recover

Click the file and preview it. Then, select the files you want to recover and click the "Recover" button. You can save your data to local and cloud drives.

recover lost files on external hard drives

If the "the disk you inserted was not readable by this computer" error still exists after trying all the methods, we recommend you back up the drive. Purchase a new device and be prepared for a drive failure soon.

How to Avoid External Disk Not Readable on Mac

Repairing the unreadable disk is time-consuming. Thus, you should take measures to protect your disk. Here are some solutions to avoid an unreadable disk on Mac.

  • Eject/inject the external drive appropriately.
  • Back up your data to avoid data loss
  • Keep advanced file system formats with the disk
  • Let anti-virus protect your MacBook or iMac

Conclusion

We listed four solutions to help you fix the "the disk you inserted was not readable by this computer" error on Mac. If you have the same issue on your drive, follow the tips on this page for help. Some of you may lose some useful files during the process, don't worry.

EaseUS Data Recovery Wizard for Mac can scan and find all your files in only a few clicks. It's your turn to make your drive work normally again.

The Disk You Inserted Was Not Readable by This Computer FAQs

Read the questions and answers below to get additional help.

1. How do I fix the disk you attached was not readable by this computer on Mac?

To fix the disk you attached was not readable by this computer, follow the solutions below:

  • Fix 1. Run a preliminary checking
  • Fix 2. Check the file system and reformat to Fat32
  • Fix 3. Update the drivers on Mac
  • Fix 4. Repair with Disk Utility
  • Fix 5. Initialize the disk
  • Fix 6. Ask a professional for help

2. How do I fix an unreadable SD card on my Mac?

Don't worry if your SD card not reading on Mac, and you can fix the error with effective solutions:

  • Open and Check SD Card
  • Check If the Physical Switch of the SD Card Is Locked
  • Check If the SD Card Reader Is Broken or Not Inserted into Mac Correctly
  • Check If SD Card Shows Up in Disk Utility...

3. Why is my SD card suddenly unreadable?

If your SD card becomes unreadable, its file system is probably damaged, and you need to format it before you can use it again.

4. Can I recover files from an unreadable SD card?

Yes, you can recover an unreadable SD card with the steps below:

  • Select the SD card to scan
  • Check for scan results
  • Choose desired files and click Recover.

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Updated by Brithny

Brithny is a technology enthusiast, aiming to make readers' tech life easy and enjoyable. She loves exploring new technologies and writing technical how-to tips. On her spare time, she loves sharing things about her favorite singer - Taylor Swift on her Facebook or Twitter.

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Written by Roxanne

Roxanne is one of the main contributors to EaseUS and has created multiple posts on digital devices like PCs, Mobile phones, tablets, Mac, etc. She loves to share ideas with people of the same interest.

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