Most of usa utilise some kind of external storage device with our Mac at some fourth dimension or some other, whether it's a USB stick, flash drive, external hard deejay, or SSD. Most of the fourth dimension, there's no problem. However, yous may encounter errors now and again, and ane of the about common is that your Mac is unable to write to the disk. You may see a message telling yous that the drive is read-only. Fortunately, information technology'due south non too difficult to ready the trouble. In this article, nosotros'll show you how.

What causes the "read-only" error?

There are two possibilities when you see a message telling you a difficult drive, USB stick, or other external storage media is read-simply.

  1. The drive is formatted in a way that means your Mac can read information technology but non write to information technology. This can happen with disks that are formatted as NTFS.
  2. Some permissions settings prevent your Mac or your user account from writing to the disk.

To determine which of these is causing the problem, select the deejay in the Finder and press Command-I, or right-click it and choose Get Info.

Under General, you should meet a listing of parameters. Look at the one named Format. If information technology says NTFS, that's the problem.

If the Format is APFS, macOS Extended, or FAT 32, so that is non the problem, and you'll need to check permissions.

  1. Await at the lesser of the Get Info window.
  2. Under Sharing & Permissions, it volition tell you what admission you lot take. If information technology says "read-merely," you know the problem is permissions-related.

Tip:

CleanMyMac 10's Maintenance module allows you lot to repair broken permissions on a deejay with a couple of clicks. That might be all you need to exercise to set problems with only beingness able to read from external disks.

Repair disk permissions in Maintenance module CMMX

How to modify permissions on an external hard bulldoze on your Mac

The following applies whether the bulldoze in question is a difficult drive, USB stick, SSD, or any other external media. There are several options, depending on what you identified as causing the problem.

How to fix hard drive read-only issue

There are two options here. I is to reformat the bulldoze to a format your Mac can write to too as read. This will wipe all the data from it, and then you should make a backup or manually copy of import files to another location first. Depending on how y'all format it, information technology may as well crusade bug if you need to utilize the drive with a Windows PC. So, only choose this option if you know the drive will simply exist used with Macs in the future.

The other selection is to use third-party driver software to enable your Mac to write to an NTFS-formatted disk. At that place are a number of paid-for and some complimentary options available.

How to reformat an external drive:

  1. With the drive plugged into your Mac, become to Applications > Utilities and launch Disk Utility.
  2. Choose the external disk in the Deejay Utility sidebar.
  3. Select the Erase tab.
  4. Type in a name for the reformatted drive.
  5. Select MacOS Extended (Journaled) from the dropdown card.
  6. Press Erase.
  7. The drive will be wiped, reformatted, and when it'due south washed, your Mac volition be able to write to information technology.

How to fix permissions problems

If the bulldoze is correctly formatted for the Mac and y'all can't write to it, the problem is likely to be related to permissions. Here's how to ready it.

  1. Select the bulldoze in the Finder.
  2. Printing Control-I to display the Get Info window.
  3. At the bottom of the window, click the pointer adjacent to Sharing & Permissions to display permissions.
  4. Click on the Privilege bill of fare adjacent to your username and choose Read & Write.
  5. Close the Get Info window.

If your user business relationship is not an admin user, you may have to utilise the padlock to unlock permissions settings and type in an admin username and countersign. You may too demand to restart your Mac to get the change to take effect.

In some circumstances, you may not be able to modify permissions in the Finder, or doing so may not gear up the problem. If that happens to y'all, the next step is to apply Disk Utility to set up the deejay.

  1. Become to Applications > Utilities and launch Deejay Utility.
  2. Select the external disk in the sidebar.
  3. Click on Outset Aid.
  4. Printing Run to ostend that you lot want to endeavour and repair the disk.

In versions of macOS up to and including macOS 10.x Yosemite, you could utilise Deejay Utility to repair permissions. The option appears in the First Assistance tab with ii buttons, one to verify and ane to repair permissions. If you lot are running a version of macOS where these options are available, y'all should utilise them instead of the steps described to a higher place.

If yous encounter an outcome where a hard bulldoze is read-just on your Mac, or perhaps a USB stick or flash drive, it may exist that it is formatted as NTFS, which can be read by macOS but non written to. It may besides exist a permissions issue. If you follow the steps in this article, you lot'll be able to identify which information technology is and set up it rapidly.