What to Do If External Hard Drive Is Read Only on a Mac

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external hard drive read only

If you are unable to write on an external hard drive on Mac, its permissions are probably set to “Read Only.” It’s definitely possible that you set your Mac external hard drive to “Read Only” and forgot, but there are other issues that can cause this symptom.

Below are all the ways to fix an external hard drive that is “Read Only” on a Mac, according to what exactly caused it. At the end of this article, you’ll know what to do next. Read on.

Why is External Hard Drive Read Only on Mac?

There are 3 common reasons why an external hard drive is “Read Only” on Mac. Knowing which one of these applies to you is key to successfully fixing this issue.

  • Permission Settings. You can change an external hard drive’s read and write permissions using a computer. It’s possible that the “Read Only” permissions were carried over to your Mac when you connected your drive. This can easily be changed through Finder. Click here to jump to that section.

  • Formatting Errors. Formatting errors are a symptom of a corrupted drive. Corruption can occur due a virus attack, interruption during read and write, software issues, and/or physical damage. You can attempt to fix it using Disk Utility. Click here to jump to that section.

  • NTFS Formatting.Your drive may be formatted to NTFS. Due to compatibility issues, NTFS is “Read Only” on Mac (but “Read & Write” with Windows). In other words, using an NTFS drive means that you don’t have permission to write to your external drive on Mac. The solution is to format your drive. Click here to jump to that section.

How to Check Permissions for External Hard Drive on Mac

Users can modify and check permissions for an external hard drive on Mac from anywhere in Finder. Here’s how:

Step 1. Right-click your external hard drive in Finder and click “Get Info.”
Right-click menu on external drive

Step 2. Scroll down to the bottom of this new window and click the toggle beside “Sharing & Permissions” to expand these settings.
Sharing permissions tab in the Get Info window

Step 3. Check if the entry under the “Privilege” column beside your name (or “everyone”) says “Read Only.” If so, that means you can’t write data to that drive.
Permissions in the Get Info window

You can also expand the “General” toggle to find out what file system your drive is formatted in. If it’s “NTFS”, you’ll need to format your drive to make it compatible with macOS. Click here to jump to the right method.

How to Fix External Hard Drive Read-Only Issue on Mac

Choosing the right solution is a matter of figuring out what the problem is, so read the first section of this article if you haven’t already. Below are 3 different ways to fix an external hard drive read-only issue on Mac.

Methods 1 and 2 are the only ways to change a hard drive from “Read Only” on Mac without formatting. Method 3 asks you to format your drive, which will wipe your data.

Method 1: Change Drive Permissions on macOS

If your drive is not formatted to NTFS and you still can’t access it, try manually changing the permissions using Finder. To change permissions on an external hard drive on Mac:

Step 1. Right-click your external hard drive in Finder and click “Get Info.”
Right-click menu on external drive

Step 2. Scroll down to the bottom of this new window and click the toggle beside “Sharing & Permissions” to expand these settings.
Sharing permissions tab in the Get Info window

Step 3. Under the “Privilege” column, click the entry beside your username (or “everyone”) and select “Read & Write.”
User's read and write permissions in Get Info window

Method 2: Use Disk Utility’s First Aid Function

If changing the permissions manually doesn’t work, your drive may have disk errors. The native macOS tool Disk Utility, which has a tool called “First Aid” that automatically scans for and repairs errors. To use FIrst Aid to fix an external drive or USB drive read only on Mac:

Step 1. Open Finder > Applications > Utilities > Disk Utility.
Disk Utility icon in the Finder Applications folder

Step 2. Click the “View” button on the top-left corner of the middle pane and select “Show All Devices.”
Show All Devices button in Disk Utility

Step 3. Select your external hard drive from the list and click the “First Aid” button at the top of the Disk Utility window.
First Aid button in Disk Utility

Step 4. In the dialogue box that appears, click “Run.”
Run First Aid button in Disk Utility

Method 3: Format Your Drive

macOS can natively read & write on FAT32 and exFAT disks, so you’ll need to format your drive to one of these file systems. You can easily do this using Disk Utility:

Formatting totally wipes all data from the disk. You will have to use a tool called “Data Recovery Software” to restore your data after formatting it. If your data matters to you, read (and understand) this section of the article about data recovery before proceeding.

Step 1. Launch Disk Utility (Finder > Applications > Utilities > Disk Utility).
Disk Utility icon in the Finder Applications folder

Step 2. Click the “View” button on the top-left corner of the middle pane and select “Show All Devices.”
Show All Devices button in Disk Utility

Step 3. Select your external hard drive from the list and click the “Erase” button at the top of the Disk Utility window.
Erase button in Disk Utility

Step 4. Name your external drive, choose “ExFAT” for the format, and “GUID Partition Map” for the Scheme. Then, click “Erase.”
Format settings in Disk Utility

How to Recover Data From an External Hard Drive after Formatting

After formatting your drive from NTFS to FAT32 or ExFAT (or other macOS-compatible file systems), the data on your drive gets totally wiped. There’s no way to access them in Finder – you’ll need to use data recovery software.

We’ll demonstrate this process using a tool called Disk Drill. It’s a highly effective and easy-to-use data recovery software that we often feature on Macgasm. Here’s how to use it:

Disk Drill requires that your Mac recognizes your drive. To recover an external hard drive that is not showing up, you have to first get it to appear on Disk Utility.

Step 1. Securely connect your external drive to your Mac, then download and install Disk Drill.

Step 2. Launch Disk Drill by opening Finder > Applications and double-clicking its icon.
Disk Drill icon in Finder Applications

Step 3. Select your external drive and click “Search for lost data.”
Disk Drill drive selection screen

Step 4. Once Disk Drill completes the scan, click “Review found items.”
Disk Drill scanning screen

Step 5. Quickly filter results by using the left sidebar and the search bar in the top-right corner of the window.
Disk Drill search bar and filter sidebar

Step 6. You can find out if you’re able to recover the file you want by previewing it. Hover your mouse pointer to the right of any file and click the eye button that pops up.
Disk Drill file preview

Step 7. To select the files you want to restore, use the checkboxes in the left-most column. Then, click “Recover.”
Disk Drill file selection

Step 8. Select a location on your computer where you want Disk Drill to save your files. Then, click “OK.”
Disk Drill save recovered files dialogue

Disk Drill Basic for Mac does not offer free data recovery, but you can preview as many files as you want. This should tell you if the files you need are recoverable. “Free” data recovery software does exist, but they all have their own limitations – your mileage may vary.