Almost of us use some kind of external storage device with our Mac at some time or another, whether it's a USB stick, wink drive, external hd, or SSD. About of the fourth dimension, there'due south no trouble. However, you lot may encounter errors now and again, and one of the almost common is that your Mac is unable to write to the disk. You may run across a message telling y'all that the drive is read-but. Fortunately, it'south not too difficult to gear up the problem. In this article, we'll bear witness you lot how.

What causes the "read-just" error?

At that place are two possibilities when you see a message telling you a hard drive, USB stick, or other external storage media is read-only.

  1. The drive is formatted in a fashion that ways your Mac can read information technology but not 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 deejay.

To determine which of these is causing the trouble, select the disk in the Finder and printing Command-I, or correct-click information technology and cull Get Info.

Under General, you should encounter a list of parameters. Await at the 1 named Format. If it says NTFS, that'south the trouble.

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

  1. Look at the bottom of the Get Info window.
  2. Under Sharing & Permissions, it will tell you what access you take. If it says "read-only," you know the trouble is permissions-related.

Tip:

CleanMyMac 10's Maintenance module allows y'all to repair broken permissions on a disk with a couple of clicks. That might be all you lot need to practise to gear up problems with simply being able to read from external disks.

Repair disk permissions in Maintenance module CMMX

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

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

How to fix hard drive read-simply issue

At that place are two options here. I is to reformat the drive to a format your Mac tin can write to also as read. This will wipe all the data from it, so you lot should make a backup or manually copy important files to another location showtime. Depending on how y'all format information technology, it may also cause bug if y'all need to apply the drive with a Windows PC. And so, simply choose this option if you know the bulldoze will only be used with Macs in the futurity.

The other selection is to apply third-party driver software to enable your Mac to write to an NTFS-formatted deejay. In that location are a number of paid-for and some free options available.

How to reformat an external bulldoze:

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

How to fix permissions problems

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

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

If your user business relationship is non an admin user, you may have to use the padlock to unlock permissions settings and type in an admin username and countersign. You may also demand to restart your Mac to go the change to have outcome.

In some circumstances, yous may not exist able to modify permissions in the Finder, or doing so may non set up the problem. If that happens to you, the adjacent step is to apply Disk Utility to ready the disk.

  1. Go to Applications > Utilities and launch Deejay Utility.
  2. Select the external disk in the sidebar.
  3. Click on First Aid.
  4. Press Run to confirm that you want to attempt and repair the disk.

In versions of macOS up to and including macOS 10.10 Yosemite, you could utilise Deejay Utility to repair permissions. The option appears in the Starting time Aid tab with two buttons, ane to verify and ane to repair permissions. If yous are running a version of macOS where these options are bachelor, you should use them instead of the steps described above.

If yous encounter an issue where a difficult drive is read-only on your Mac, or perhaps a USB stick or flash drive, it may exist that it is formatted equally NTFS, which tin can be read past macOS but not written to. It may also be a permissions issue. If you lot follow the steps in this article, you'll exist able to identify which information technology is and gear up information technology speedily.