Troubleshooting External hard drive read-only on Mac

One of the most common issues that Mac users face while using external hard drives is the read-only error. That means when you plug your external hard drive into Mac, you can view the information stored on the drive, but you can’t add or remove data. This’s a very strange occurrence.

The reasons may lie in the incompatible file system, read-only permission, or corrupted disk.

The good news is that you can change your external hard drive from read-only without the help of a technician.

In this post, we will further explain the reasons and give detailed solutions to this problem.

External Hard Drive ‘Read Only’ on Mac? Fix It Now

STEP 1 – The file System is NTFS

The first detail to check is if the drive is formatted to NTFS format.

You can see the file system in the information window as well as in Disk Utility.

If you find the disk is formatted with the Windows NT file system developed by Microsoft, the incompatibility of the file system is the cause.

As the name suggests, NTFS is optimized for Windows only. Now, the Mac machine allows users to read files on NTFS drives but not to write.

How to fix:

Method 1- Format the external hard drive

In this situation, you can easily fix the read-only issue by reformatting the device to FAT or ExFAT, which is fully compatible with both Windows and macOS, and it is beneficial if you frequently switch between Mac and PC.

It is a good option if you don’t have any important information on the drive.

Step 1: Back up files by dragging the files from the drive to the Mac desktop if you do have a few important files you don’t want to lose.

Moving files out of the drive are possible on Mac if you have an NTFS-formatted drive.

Step 2: Open Disk Utility.

Step 3: Select the external hard drive in the drive list.

Step 4: Click Erase.

Step 5: Enter a name, choose FAT or ExFAT in the Format section, and GUID Partition Map in Scheme section.

Step 6: Click Erase to confirm.

Method 2: Use NTFS for Mac tool

If you have a lot of important files on the drive, reformatting is definitely not the best solution. Fortunately, there are some NTFS for Mac utilities which can help you write to NTFS drives.

Free NTFS for Mac tools including Mounty for NTFS and NTFS-3G need complicated installation and slow read-write speed.

If you need to use the utility very frequently, it is always recommended that you use a commercial one because it doesn’t cost much.

Step 1: Free download and install an NTFS for Mac software on your Mac from

Step 2: Plug the NTFS drive in your Mac and the disk will be automatically mounted in read-write mode.

Step 3: Write to the NTFS volumes successfully.

Write to the NTFS volumes successfully

STEP 2 – The disk permission setting is read-only

Being a multiuser operating system, macOS sets up access permission settings for all files and folders on the system, including external drives. If the external drive is used on a different Mac, the permissions settings may prevent full access to the drive.  

How to fix:

Method 1: Ignore ownership on this volume

You can change the permissions on the external hard drive by ignoring the ownership but you need to know the administrator password.

Step 1:Right-click your external hard drive shown on your Mac and select Get Info. The external hard drive’s information window opens.

Step 2 Unfold the Sharing & Permissions section.

Step 3 – Hit on the lock icon and provide the admin password.

Step 4:Check the “Ignore ownership on this volume” at the bottom of the window.

Sharing & Permissions section.

Method 2 – Change the read-only privilege to Read & Write

Another way you can alter the read-only permission is to change the status under Privilege.

Step 1: Stay on the Get Info window.

Step 2: Click lock icon to make changes.

Step 3: Input the correct password.

Step 4: Find your user name and click the small up/down arrow on the right to choose Read &Write.

The file system on the external hard drive is corruption

Some disk errors will cause the external hard drive to be read-only as well. In many cases, disk errors are minor and the system may determine to mount the external disk in read-only mode to prevent the data it from corruption.

How to fix:

Method 1: Repair the external hard drive with Disk Utility.

Step 1: Head to Application > Utilities > Disk Utility.

Step 2: Choose the read-only external hard drive from the left sidebar.

Step 3: Click First Aid in the top center, and then click Run.

After the repair process is completed, the read-only error on the disk will be fixed and you would be able to use the disk as usual.

Disk Utility

Method 2: Format the external hard drive

Formatting can fix all software errors that make the external hard drive not work. Go back to the first section to know how to format a disk with Disk Utility.


Generally, the external hard drive read-only issue is mainly caused by the NTFS file system, disk permission, and disk errors.

But these can be easily fixed by using an NTFS for Mac tool, by changing the disk permissions, and by repairing the drive using Disk Utility.

Nevertheless, if all the solutions failed anyhow, it could be a hardware malfunction in the external hard drive, in which case it would be best to replace it.

Saurabh Tiwari

I am Saurabh, working as webmaster and content writer at Techibhai. I love to interact with minded blogger and write about SEO, Web design, Development trick and much more.

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