The disk can’t be read: understand what it means and how to fix it

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If you have come across the message “disk cannot be read” after inserting an external disk, USB flash drive or other external storage device, don’t worry, we will help you!

Although this is not normal and the error message does not indicate the cause of the problem, you can try to fix it with a few basic steps that can prevent the loss of data and information from your device.

Stay with us and find out what it is and how to fix the “disk cannot be read” error in Apple’s operating system, macOS!

O disco que você inseriu não podia ser lido por este computador
O disco que inseriu não pode ser lido por este computador

What does “The disk you inserted cannot be read by this computer” mean?

This error occurs when, for some reason, your Mac is unable to read the data on a hard disk (external disk) or USB flash drive. This can occur for a number of reasons, in particular a problem with the device itself.

However, the error can also be caused by problems with the operating system, such as outdated drivers, etc. In these cases, detecting and fixing problems in the operating system can be a viable alternative. Make sure you always keep your drivers and system up to date to avoid possible errors.

When it comes to the device itself, some of the possible reasons why the computer can’t read the disk are:

Disk failure

Devices can fail from time to time, especially when they are old and worn out. The disk may have some mechanical damage or even the USB port may be worn out if the drive has been connected and disconnected several times.

Corrupted file system or partition table

The file system format can vary from device to device and this can cause incompatibilities between different devices.

In addition, the operating system needs to understand the device’s partition table in order to understand how the disk organizes the data stored there. If this information happens to be corrupted, the computer will not be able to read the data.

A new disk

A new disk may have no partition information, resulting in the error described above. These disks are also called “uninitialized disks”.

Virus attacks

Viruses can attack by rewriting the disk’s data structure, making it unreadable to the operating system.

How to fix the error “The disk you inserted cannot be read by this computer”?

There are several ways to fix this error, depending on its cause. Some options you should try are:

1. Try another USB port

If the problem is caused by damage to the USB port, testing another port may solve the problem. If this doesn’t work, also try changing the USB cable used to connect the disk to the computer, as this could be the source of the problem.

If you find that the USB port is the problem, you can try to solve the problem by resetting the SMC.

2. Check the file system format

A disk’s file system needs to be compatible with the operating system in order to operate normally. In the case of the Mac, the file system must be FAT32 or HFS. If the file system is something else, such as NTFS, the Mac will be able to read the files, but it won’t be able to make changes or write new data. For full access to the disk’s features, you will need to format the disk by converting it to FAT32 or HFS.

However, by formatting the disk, the data will be lost. If you need this data, back up the disk to another compatible operating system before formatting it.

3. Check or repair unreadable disk (flash drive, SD card)

The Mac has its own feature for checking and repairing possible disk errors, especially file system errors. To use it, follow the steps below:

  1. In “Applications”, go to “Utilities”;
  2. Click on “Disk Utility”;
  3. With the device connected to your Mac, select the unreadable disk from the left side menu;
  4. Click on the “First Aid” button at the top of the Disk Utility window;
  5. When a window appears asking if you want to run First Aid, click “Run”;
  6. The process should start and may take a few minutes. It will try to detect and repair possible problems;
  7. When the process has finished, click “Done” and eject the disk safely;
  8. Plug the disk back into your Mac.

4. Initialize the disk to access the data

In the case of a new disk, it is necessary to assign the information of the logical parts so that the operating system can access it. On a partition disk, there is a section called the “Master Boot Record” (MBR), designed for storing information.

On old, used disks, the MBR needs to be recreated if it is corrupted and impedes access to the disk. This process is called “initialization”.

During this process, the disk is formatted and logical errors are corrected. Because of this, you should only do this when you already have a backup of your data, if you don’t want to lose it.

To initialize, follow these steps:

  1. Open Disk Utility;
  2. Select the unreadable disk from the left side menu;
  3. Click on the “Erase” button (eraser icon) at the top of the Disk Utility window;
  4. Give the drive a name and select the appropriate file format;Click on “Erase”.

This process will format the drive and leave it in the correct file system, allowing the disk to be read by the computer.

To understand how to access your data after formatting, read our article on 11 ways to recover a formatted disk.

What do I do if I can’t access the data on the disk?

There are various ways of trying to regain access to the disk, but they don’t always work. In these cases, it is also important not to attempt too many procedures to avoid further damage to the device. This is also when you should seek the help of a professional.

A professional can help detect other possible problems that the device may be experiencing, as well as employ advanced techniques to restore data from the disk.

Bot has been a leader in data recovery for more than 10 years, with more than 60,000 successful cases and a 99% approval rate. It is present in several Portuguese cities, with specific and assertive methods that guarantee a high data recovery rate in cases like this.

If you need help, fill in this form to get assistance from Bot.

How do I access my Mac’s hard disk?

If you use the macOS operating system and don’t know how to check the details on your hard disk, it’s quite simple. According to Apple Support, all you have to do is access “Disk Utility” to check and repair errors, format and manage volumes on storage devices and solve problems that occur on the disk.

You can use it in two ways:

  • Click on Launchpad, type “Disk Utility” in the search field and click on the icon;
  • In Finder, by pressing “Go”, then “Utilities” and double-clicking on ‘Disk Utility”.

An overview of the disk unreadability error in Mac

There isn’t a very complex answer to this unreadability error. It usually appears when the user tries to open the storage devices on a computer running the macOS system.

But calm down! It doesn’t happen every time! The message usually appears when the device (or the files on it) has a problem that prevents the system from reading it properly.

What makes a disk unreadable by a Mac computer

As we mentioned above, there are many different causes. As such, we can’t know exactly why the disk can’t be read. However, the main causes are:

  • Disk failure;
  • Corrupted file system or partition table;
  • A new disk;
  • Virus attack.


Certainly, the inability to read a disk on a macOS system can cause some setbacks. However, it is important to note that the problem has some solutions that usually work.

And if even after trying you can’t access your device, don’t worry, Bot Data Recovery can help you! We have over 10 years’ experience and are leaders in professional information recovery.

Don’t lose your data due to everyday problems. Contact us and get all your questions answered! Our team of experts is ready to help you.


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