Most of usa use some kind of external storage device with our Mac at some time or another, whether it's a USB stick, flash bulldoze, external hard disk, or SSD. Nigh of the time, at that place's no problem. All the same, you may meet errors at present and again, and one of the well-nigh common is that your Mac is unable to write to the disk. You may see a bulletin telling you that the bulldoze is read-but. Fortunately, information technology'due south not as well difficult to fix the trouble. In this commodity, we'll evidence you lot how.

What causes the "read-only" error?

At that place are ii 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 way that means your Mac can read it but non write to it. This can happen with disks that are formatted equally NTFS.
  2. Some permissions settings forestall your Mac or your user business relationship from writing to the deejay.

To decide which of these is causing the trouble, select the disk in the Finder and press Command-I, or right-click it and choose Become Info.

Under General, you should see a list of parameters. Wait at the one named Format. If it says NTFS, that'south the problem.

If the Format is APFS, macOS Extended, or FAT 32, then that is non the trouble, and you'll need to cheque permissions.

  1. Look at the bottom of the Become Info window.
  2. Nether Sharing & Permissions, it volition tell you what admission you take. If information technology says "read-merely," you lot 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 exist all you demand to exercise to set problems with only being able to read from external disks.

Repair disk permissions in Maintenance module CMMX

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

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

How to fix hard drive read-only result

There are ii options here. One is to reformat the drive to a format your Mac tin write to as well as read. This will wipe all the data from it, so you should make a backup or manually copy important files to some other location first. Depending on how you format it, it may also cause problems if you need to utilise the drive with a Windows PC. So, merely choose this option if you know the drive will only be 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. There are a number of paid-for and some complimentary options available.

How to reformat an external drive:

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

How to ready permissions problems

If the drive is correctly formatted for the Mac and you tin can't write to it, the trouble is probable to be related to permissions. Here's how to fix information technology.

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

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

In some circumstances, you lot may not be able to change permissions in the Finder, or doing so may not fix the trouble. If that happens to you, the next step is to use Disk Utility to set up the disk.

  1. Become to Applications > Utilities and launch Disk Utility.
  2. Select the external disk in the sidebar.
  3. Click on First Assistance.
  4. Press Run to confirm that you want to endeavour and repair the disk.

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

If you come across an issue where a hard bulldoze is read-just on your Mac, or maybe a USB stick or wink drive, it may be that it is formatted as NTFS, which can exist read past macOS but non written to. Information technology may too exist a permissions issue. If you follow the steps in this commodity, y'all'll be able to identify which it is and fix it quickly.