Well-nigh of us use some kind of external storage device with our Mac at some time or another, whether it's a USB stick, flash drive, external hard deejay, or SSD. Well-nigh of the time, there's no trouble. However, yous may encounter errors now and once again, and i of the most common is that your Mac is unable to write to the deejay. Y'all may see a bulletin telling you lot that the drive is read-only. Fortunately, information technology's not too difficult to prepare the problem. In this article, we'll bear witness y'all how.

What causes the "read-only" error?

In that location are two possibilities when yous see a message telling you a difficult drive, USB stick, or other external storage media is read-only.

  1. The drive is formatted in a way that means your Mac can read it only not write to it. This tin can happen with disks that are formatted as NTFS.
  2. Some permissions settings forbid your Mac or your user account from writing to the deejay.

To make up one's mind which of these is causing the problem, select the disk in the Finder and press Control-I, or right-click information technology and choose Become Info.

Under General, you should encounter a list of parameters. Look at the one named Format. If information technology says NTFS, that'due south the problem.

If the Format is APFS, macOS Extended, or Fatty 32, then that is not the problem, and you lot'll need to check permissions.

  1. Look at the bottom of the Become Info window.
  2. Under Sharing & Permissions, it will tell you what access you have. If it says "read-only," y'all know the problem is permissions-related.

Tip:

CleanMyMac X's Maintenance module allows you to repair broken permissions on a disk with a couple of clicks. That might be all you demand to exercise to gear up problems with just beingness able to read from external disks.

Repair disk permissions in Maintenance module CMMX

How to modify permissions on an external difficult drive on your Mac

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

How to prepare hard drive read-only result

In that location are two options here. Ane is to reformat the bulldoze to a format your Mac tin write to every bit well as read. This volition wipe all the data from it, so yous should make a backup or manually copy of import files to some other location first. Depending on how you lot format it, information technology may besides cause problems if you need to use the drive with a Windows PC. So, only choose this option if you know the bulldoze will simply be used with Macs in the futurity.

The other option is to employ third-party commuter software to enable your Mac to write to an NTFS-formatted disk. At that place are a number of paid-for and some free options available.

How to reformat an external drive:

  1. With the drive plugged into your Mac, get 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 proper name for the reformatted bulldoze.
  5. Select MacOS Extended (Journaled) from the dropdown menu.
  6. Press Erase.
  7. The drive will exist wiped, reformatted, and when it's done, your Mac will be able to write to it.

How to fix permissions problems

If the drive is correctly formatted for the Mac and you tin't write to information technology, the problem is likely to be related to permissions. Here's how to ready it.

  1. Select the bulldoze in the Finder.
  2. Press Command-I to brandish the Get Info window.
  3. At the bottom of the window, click the arrow next to Sharing & Permissions to brandish permissions.
  4. Click on the Privilege menu next to your username and cull Read & Write.
  5. Close the Get Info window.

If your user account is not an admin user, you may accept to employ the padlock to unlock permissions settings and type in an admin username and countersign. You may also need to restart your Mac to get the change to take effect.

In some circumstances, you may not be able to change permissions in the Finder, or doing so may not fix the problem. If that happens to you, the side by side footstep is to use Deejay Utility to ready the disk.

  1. Go to Applications > Utilities and launch Disk Utility.
  2. Select the external deejay in the sidebar.
  3. Click on Showtime Help.
  4. Press Run to confirm that you lot desire to endeavour and repair the disk.

In versions of macOS upward to and including macOS 10.ten Yosemite, y'all could use Deejay Utility to repair permissions. The option appears in the Kickoff Assistance tab with two buttons, 1 to verify and i to repair permissions. If you lot are running a version of macOS where these options are available, you should use them instead of the steps described above.

If yous come across an issue where a hard drive is read-merely on your Mac, or peradventure a USB stick or flash bulldoze, it may be that it is formatted as NTFS, which can exist read by macOS but non written to. It may also be a permissions upshot. If y'all follow the steps in this article, you'll exist able to place which it is and gear up information technology quickly.