How to access an external drive that's not recognized on a Mac

2.3M views
12 min read

Most of the time, when you connect an external hard drive to your Mac’s USB port, you soon see it mount on the desktop. Apple likes to ensure these are easy to find, so they also appear in the Finder in the left-hand column under Locations.

However, sometimes, an external hard drive doesn't show up. It’s annoying, especially when you need to transfer something right then. And besides, there can be a risk that data on the external USB pen, hard, or flash drive is corrupt, which means you can’t transfer what you need between devices at all.

Corrupt data can be one reason your Mac won't recognize an external drive, but there are other reasons too. Let’s take a look at why this is happening and how you can fix the external hard drive not showing up problem:

Why your Mac does not recognize external hard drive 

Let’s say you’ve encountered the problem of SSD not showing up. There could be a few reasons why SSD isn’t making an appearance (just as any other external drive), the most common being:

How to fix an external disk drive that won't show up on a Mac

While it’s impossible to instantly figure out why an external disk drive is not showing up, you have to try to fix the problem.

Start with the basics:

  1. Check whether the drive is properly plugged in. It sounds obvious, but since this relies on a wire - either a USB cable or HDMI cable - if it’s not connected properly then it won’t appear on your desktop.
  2. Faulty cable. Assuming it’s plugged in correctly, not wobbly or loose, the cable could be at fault. Try connecting the same device with a different cable.
  3. Damaged USB or flash drive port. It could be a hardware issue with the Mac. If you’ve got another port, try connecting the device to that one.
  4. Reboot your Mac. Sometimes, if a USB disk won't boot, the cause is a macOS issue. Hopefully, some data damage can be fixed by restarting. Choose the Apple menu > Restart. Or press and hold the power button and, when a dialog box appears, click Restart or press R.  Restarting your Mac essentially clears your macOS’s memory and starts it up fresh. 
  5. Incorrectly formatted drive. Not every external drive is optimized for Macs. It could be that you are trying to connect something only fit to interact with Windows devices. If you’ve got a PC or laptop, it’s worth connecting and seeing if you can access the files through another device. The best way to look for an incorrectly formatted drive is to go to
    Apple (in the top toolbar menu) > About This Mac > Storage.
    See if the external drive shows up here. For more information, go to the same menu option, then select System Report.

    Storage information

  6. Mac not formatted to display external drives on the desktop. It could be that your Mac already recognizes the device, but just isn’t showing its icon on the desktop screen. Even if that is the case, the drive will still appear in the left-hand column of the Finder menu under Locations. You should be able to access your drive that way, and, in the Finder menu under Preferences > General, you can check External Drives to ensure that from now on it shows up on your desktop too.
  7. Reset NVRAM. To do this, shut down or restart your Mac, switch it back on and immediately press these four keys together for at least 20 seconds: Option, Command, P, and R. It should look as though your Mac has started again; if it has, release the keys when you hear the second startup chime. Hopefully, the hard drive has shown up now.
  8. Check Apple’s Disk Utility to see if an external drive is showing up. Disk Utility is within System Preferences, or you can find it using Spotlight. If it is visible, then click the option to Mount, which should make it visible on the desktop and in the External Drives option in the Finder menu.

Unfortunately, if none of those options has worked and you continue having the external hard drive not showing up problem, then it could have crashed, or be well and truly broken. But there might still be a way you can recover the data on the external drive

How to fix new hard drive not showing up in Finder

When you connect a drive to Mac, it should appear in Finder under Locations. What to do if external hard drive is not detected? In most cases, when Finder doesn’t see your drive, you just have to change a few things in Preferences. However, sometimes, there are more serious problems such as insufficient power supply. Let’s see how you can fix these things. 

How to show connected devices in Finder

  1. Go to the Finder menu > Preferences 

  2. In General, click on External disks to ensure that from now on it shows on the desktop.

In the Sidebar tab, you can choose which folders and devices will be shown in the left-hand column of the Finder window.

Recognize an external drive with Finder Preferences

How to add cloud storages to Finder

You can also mount cloud storage as a local drive on your Mac. By connecting Google Drive, Dropbox, or Amazon to your computer, you get more space for securely accessing and sharing files. For your ease, add cloud drives to Finder with CloudMounter so that you keep them close at hand. You can read detailed instructions on managing cloud storage as local drives here.

mount cloud storage as a local drive

Repair the failed external drives with First Aid

The most direct reason your external hard drive could be detected by macOS but can't be opened is the file system problem. If your drive is having such problems, you can try to fix them yourself with First Aid and therefore get access to your files.

First Aid tool will check the disk for errors and then attempt a repair as needed. It helps to verify and repair a range of issues related to startup HD and external drive problems. If you are able to fix the hard drive or SSD in your Mac (or any external drive) using Disk Utility you will hopefully be able to recover your files.

To run Fist Aid on an external hard drive:

  1. Open Disk Utility. You can search for it using Spotlight or via Finder > Go > Utilities
  2.  Check on your external hard drive, click the First Aid tab and select Run to start running diagnostics.

Run First Aid

How to recover data from a crashed drive

If First Aid has been successful in fixing errors, the external drive should be available to mount. If the utility hasn’t repaired issues, your drive truly is broken or formatted using a file system that the Mac cannot read — in this way you have to recover data from a damaged disk drive.

Thankfully, there is an app for that. Disk Drill is the world’s premier data recovery software for Mac. Powerful enough to retrieve long-lost, mistakenly deleted files from Macs, external hard drives, USB drives, and camera cards.

An easy way to recover lost files on an external hard drive

Here’s how to recover files with Disk Drill (pro version available on Setapp):

  1. Connect your drive to the Mac.
  2. Quit all other applications on the Mac, especially those that may be trying to access the external drive (e.g. iPhoto, Words)
  3. Launch Disk Drill.
  4. Click on the external drive that you are trying to recover files from. If it has partitions, you will see all of them. If, however, you still don’t see any volume to the external drive then you may need to try some of the steps above again or read the Disk Drill Scanning FAQs.
  5. To avoid the external drive being accessed during the recovery process, click Extras next to the drive or drive partition or file, then select Remount Volume As Read Only. A padlock will appear, protecting the drive during the process.
  6. Now click Rebuild (or Recover) next to the file(s) you are trying to recover. Once the scan is finished - it may take some time if the files are large - a list of files will appeal. 
  7. Next, click Mount Found Items as Disk button on the bottom-left below the scan results.
  8. Disk Drill "strongly suggests saving the files to a different drive than the one you are trying to recover files from. Saving to the same drive substantially lowers your chances of recovery."
  9. A drive icon will appear, which once you double click will give you the option to open the files as you would do before they were lost. Drag them to another location, such as your desktop or a folder on your Mac.
  10. Open the files to ensure they have been recovered properly and safely eject the external drive.

Disk Drill does have other ways to recover lost files but assuming there are no complications, this method is the most effective.

A few more tips on getting your files back

  1. Macs and third-party apps that look after Macs, such as Disk Drill and iStat Menus come with a S.M.A.R.T. (also known as Self-Monitoring, Analysis, and Reporting Technology) status monitor. If a SMART check reports errors, then it could mean the hard drive is at risk of failing completely. Within Disk Utility and Disk Drill, there are several solutions for this: Repair Disk Permissions and Repair Disk. If neither of them works, it’s recommended to back up all of the data from the disk, erase it, then run a SMART check again. The external hard drive should show up as Verified.
  2. Partitions can get lost within hard drives, temporarily hiding all of the information contained within. Disk Drill can help to identify and restore this information.
  3. Within Disk Drill, you can restore data when a hard drive is damaged or add formatting, which is also something Disk Utility can help with.
  4. CleanMyMac, another useful app available from Setapp, can help you identify external hard drive errors and repair them. It is an essential tool worth trying when you’re having external hard drive difficulties.

Alternative ways to recover data from an external hard drive

Reset the System Management Controller (SMC) if your Mac shuts down when you plug in an external hard drive. Then use a different port to connect the external hard drive. If you’ve got a battery that you can’t remove:

  • Shut down and unplug the power adapter
  • Press and hold Shift-Control-Option and the power button for 10 seconds
  • Release all keys
  • Plug the power adapter back in and switch your Mac back on.

For Macs with removable batteries, you need to switch them off, remove the battery, then press and hold the power button for 5 seconds. After that, put the battery back in, plug in the power adapter and switch the power on again.

How to fix external drive NTFS read-only problem 

External hard disk detected but not opening? One reason your Mac isn’t recognizing the hard drive is the file format. Windows uses NTFS file formats, while Macs, up until the introduction of Sierra, have used HFS+. Now, Apple has introduced the Apple File System (APFS) for newer operating systems. 

If you connect an NTFS drive, your Mac will be able to read it but not edit it. This means you can’t really complete your task (move, copy, or delete any files) as long as you experience the read-only problem. There’s an easy way to fix this with iBoysoft NTFS, an app that enables full read/write support for NTFS drives on Mac. 

manage NTFS drives on Mac

How to make Ext2/Ext3 drives readable on Mac

The common issue is Ext2- and Ext3-formatted drives are not readable on macOS. There are two ways to access such external drives on your Mac — via Linux OS or FUSE system. The easiest would be installing Linux to a secondary drive or virtual machine.

If you go with Linux installation, dual boot your Mac with Linux on another drive and use FAT32 as a transfer intermediary. If you don’t have the drive to install Linux to, use a virtual machine as an interface for it. Transferring can be done the same way – with FAT32, or via network.

Another option for reading Ext2/Ext3 disks is mounting disk with Filesystem in Userspace (FUSE). Basically, it works as an extra interface enabling file system access via specially installed modules. Here’s how to mount drives with FUSE:

  1. Install FUSE for macOS or MacFUSE as well as a fuse-ext2 module.
  2. Use the following Terminal command to enable Disk Utility’s debug menu and see all partitions: defaults write com.apple.DiskUtility DUDebugMenuEnabled 1
  3. Attach your Ext2/Ext3 drive and locate the device name via Disk Utility.
  4. In your user account, create a folder to be used as a mount point.
  5. Use the following Terminal command to mount the drive as read-only: fuse-ext2 /dev/disk2s2 /Volumes/mountpoint
  6. For write support, use the command: fuse-ext2 -o force /dev/disk2s2 /Volumes/mountpoint

And that’s not the only case where Terminal helps you access external drive. Employ the handy all-powerful Terminal, which always comes forward with solutions for difficult problems. Especially if System Information does recognize the USB or hard drive, but continues to hide it from you, disconnect the drive and try to find it using the Terminal, which you can find in Applications > Utilities.

  • Once in the Terminal, type in the command diskutil list
  • A list with information about volumes and drives should appear
  • Look for a section labelled /dev/disk_ (external, physical)
  • Make a note of the whole line after the word disk
  • Now put the following command into the Terminal diskutil info disk followed by the number or digits assigned to that disk
  • Now you should see detailed information about the drive, therefore confirming that your Mac can and does recognize it
  • Eject using the Terminal by entering the command diskutil eject disk followed by the number or digits assigned to that disk
  • Physically remove the disk from your Mac
  • Plug it back in and your Mac should recognize it.

Console is also reliable when it comes to solving tricky problems, although it isn’t always that easy to use. You can find Console under Applications > Utilities > Console or via Spotlight. Console shows if an external drive or any error is detected under the Errors and Faults tab. If no errors show up, then the problem is not caused by the device.

no errors show up in Console utility

How to fix insufficient power supply 

Another thing that might cause USB drive not showing up is that your USB cable is just not powerful enough. Typically, a USB 1.0 or 2.0 works, but there are drives that require more power. In this case, you should get another connector or use some type of USB hub to increase the power supply. If you still can’t access external hard drive, consider switching to another Mac. 

Conclusion 

Hopefully, we’ve covered the topic so you don’t have to google “external hard drive disappear from the computer” ever again. There are lots of potential solutions for a Mac not reading/writing an external hard drive. If you’re trying to connect an NTFS drive, do it with iBoysoft NTFS for Mac. If you need to add cloud storage, CloudMounter will help you. Most importantly, you’ll never have to worry about a crashed or corrupted external drive because Disk Drill will help you recover all the data stored on it. 

iBoysoft NTFS, CloudMounter, Disk Drill, and other powerful apps such as CleanMyMac X are all available via Setapp, a productivity suite that solves your tasks with apps. Give it a try for seven days free and fix all your Mac issues in one go. 

Get 220+ Mac apps for any job

Sign up to Setapp and try them for free.