Solving The “Read Only” External Hard Drive Problem On Your Mac

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read only external hard drive macTeach your Mac a new trick. If you’ve plugged a USB stick or external hard drive only to find out it’s “Read Only”, don’t panic: there’s a reason for this, and there’s a way to fix it.

Different operating systems organize files in different ways. Mac OS X, for example, uses a filing structure called HFS+ – modern versions of Windows use NTFS. These different ways of physically arranging files on a drive confuse operating systems that aren’t used to them. Windows computers cannot open HFS drives, for example. Macs can read NTFS drives, but not write to them.

Why is this? It’s complicated, but the answer basically boils down to patents. For Windows computers to read HFS drives, Microsoft would have to pay Apple… something they won’t do. Enabling Apple computers to write to NTFS drives would involve similar expense. It’s a little more complex than this, but the basic result is that your Mac cannot write to NTFS drives.

For now.

read only external hard drive mac

Like I said: don’t panic. You can fix this. You’ve got three main options:

  1. Reformat your USB drive with FAT. This format can be read by Macs and Windows PCs alike. This is probably the simplest method, but there’s one drawback: reformatting requires deleting everything on the drive, so back it up first. On your Mac you can use Disk Utility to reformat; in Windows you need to right-click the drive, then click Format. Be sure to select FAT32 as your filesystem.
  2. Turning on OS X’s built-in support for writing to NTFS. Doing so requires some confidence, as the process isn’t entirely user-friendly – and needs to be re-done for every NTFS drive you wish to mount. Check out this blog post by Prateek V. Joshi for more information.
  3. Install software that automatically allows you to read every NTFS drive. This is the simplest option, and it’s what I’m going to outline below.

Below I’ll outline the easy-to-use paid options (one of which you can get from MakeUseOf Rewards) and a slightly-more-complex free alternative.

Using Commercial Software

Let’s go over the easiest way to solve this problem first: commercial software. Paragon NTFS for Mac is easy to install, and enables NTFS writing almost instantly. Once it’s installed you won’t even notice it’s there, save for a single entry in your OS X preferences window.

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read only external hard drive

Read more about Paragon NTFS, if you’re interested. The software isn’t expensive – it runs you $20 – and it’s one of the first such programs out there to officially support Mountain Lion (10.8).

If you’d rather not pay $20, however, you’re in luck: you can pick it up for 400 points over at MakeUseOf Rewards, assuming our licenses haven’t all been snapped up. Hurry!

Paragon isn’t the only paid software for the job out there – Tuxera (which maintains the free solution outlined below) offers similar software for 25 euros ($31). Check out for more information.

NTFS-3G: The Free Alternative

Prefer a free alternative? NTFS-3G is an open source driver used by many Linux users to read and write to NTFS drives, and and you can use it on your Mac too. It’s just a matter of knowing where to find it – and the answer is this blog post from 2010. It includes the most recent download for NTFS-3G for Mac.

The installation process is easy, but pay attention during this part:

read only external hard drive

It’s probably safest to go without the caching, but there are performance advantages to using it. It’s up to you.

Of course, if you’re using Lion or Mountain Lion (and you probably are), you’ll notice this software doesn’t work. You didn’t think it would be that easy, did you?

Fixing NTFS-3G for Mountain Lion

Simply installing NTFS-3G isn’t enough if you use Mountain Lion or Lion – the free software hasn’t been updated for these releases, and doesn’t work. You’ll see warnings at boot, and none of your NTFS drives will mount.

Again: don’t panic. This blog post by Julian Xhokaxhiu has all the answers. To summarize, you need to:

  1. Install MacFUSE.
  2. Install the Fuse error fix package
  3. Install Install OS X Fuse. Be sure to check Emulate MacFUSE during installation:

read only external hard drive mac

Do all of this and you should be able to mount your NTFS drives without any problems – and write to them. Enjoy!


Incompatibilities between Macs and Windows PCs used to be a lot worse than today – the two computers had hardly any file formats in common. Those days are largely past, but a few reminders remain. NTFS hiccups are one of them.

As you can tell, though, there are ways around most computer frustrations – including this one. You can buy software that solves the problem, or you can do a little work and solve the problem for yourself using free alternatives. It’s up to you, and I want to know: which tool did you use for the job? Share in the comments below!

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Comments (58)
  • Tiago Santos

    Very clear documentation, thank you. I used the NTFS-3G free solution and it worked just fine.

  • Rushina Shah

    This worked beautifully. I use Yosemite OS X 10.10, and followed your steps for NTFS-3G and the Mountain Lion fix. Did NOT want to reformat my hard drive, and this installation took maybe 10 mins. Thank you!

  • Milk

    You the real MVP. I installed the NTFS-3G with the companion fix update programs and it’s working great. Thanks for the article

  • Lieke

    Bless you. This helps A LOT!

  • Glenn Jensen

    If you already have a working filesystem, and you get the read only situation (i.e. the -50 error), double check the SATA cable going to your drive. I had all my user directories on the second drive (first partition) and my workspace on the same drive (in a second partition) – both were showing as read only (huge hint).

    I read this, tried it, and guess what…. it was a bum cable (or one that worked it’s way lose with vibration). I spent a few bucks and got a replacement cable with a metal latch – problem solved, hours of reinstallation / reconfiguration averted.

    Reminding you that you still need to backup invaluable data (or at least have it on or dropbox)

    • Justin Pot

      I’m sorry my article wasn’t the help you were looking for, but I’m glad you figured it out! We take cables for granted, it’s often the last thing we’ll think of.

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For more details, please read our disclosure.
Affiliate Disclamer

This review may contain affiliate links, which pays us a small compensation if you do decide to make a purchase based on our recommendation. Our judgement is in no way biased, and our recommendations are always based on the merits of the items.

For more details, please read our disclosure.