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

Most of the time, when you connect an external hard drive to your Mac's USB port, it appears on the desktop and in the Finder under Locations.

But sometimes, the external hard drive doesn’t show up. Why? Personally, I’ve run into this because of corrupted data, improper formatting, and NVRAM issues. And there are plenty of other possible causes. Let’s take a look at what might be going wrong and how to fix it when your external drive isn’t showing up on Mac.

Problem	Solution
The drive not showing up	Check connection and cable
USB port issue	Try a different USB port
Drive not visible in Finder	Finder > Preferences > General > External disks
NVRAM issue	Shut down > Press Option + Command + P + R for 20 seconds
Disk not mounting	Disk Utility > Select drive > Mount
Incorrect format	Disk Utility > Erase > Choose APFS format
File system problem	Disk Utility > First Aid > Run
macOS issue	Apple menu > Restart
Recovering lost data	Use Disk Drill
Cannot write to NTFS drive	Install iBoysoft NTFS for Mac

Why your Mac does not recognize external hard drive

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

• There’s something wrong with the cable.
• There’s a power supply problem.
• Your drive has been corrupted or broken.
• The drive is not readable on macOS.
• NTFS read-only problem.

With M1 chips, the threat is very real due to the fact that it’s impossible to boot your Mac if your internal SSD fails. 

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 SSD is not showing up, there are some working methods that will help you get things right. Let’s go through the checklist.

1. Check whether the drive is properly plugged in

I know you've probably already checked this, but I still need to mention it, just in case.  Since the connection relies on a wire — either a USB or HDMI cable — if it’s not connected properly, the drive won’t appear on your desktop.

 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. 

2. Change USB ports 

A damaged USB or flash drive port on your Mac could be the reason why external drives won’t show up. If you’ve got another port, try connecting the device to that one.

3. Edit Finder Settings 

When you connect a drive to a Mac, it should appear in Finder under Locations. What to do if an 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 Settings. Let’s see how you can fix this. 

1. Go to the Finder menu > Settings.
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. 

4. Reset NVRAM 

NVRAM has to do with storing different settings, including the startup disk selection settings. Therefore, if the USB drive is not showing up, resetting NVRAM may help fix the problem with those settings.  

To reset NVRAM on an Intel-based Mac: 

1. Shut down or restart your Mac.
2. Switch it back on and immediately press these four keys together for at least 20 seconds: Option + Command + P + R. It should look as though your Mac has started again.
3. If it has, release the keys when you hear the second startup chime. Hopefully, the hard drive has shown up now.

5. Use Apple’s Disk Utility to mount external drive manually

You’ll find Disk Utility within System Settings or via Spotlight. If the external drive is visible in Disk Utility, select it and click Mount, which should make it visible on the desktop and in the Finder menu.

6. Check System Information

If the external hard drive isn’t showing up in Disk Utility, proceed to the next step: checking System Information. Go to Applications > Utilities > System Information and select USB (or Thunderbolt if applicable).

Is your external drive listed there? If it appears in System Information but not in Disk Utility, it might mean that the system has detected the hardware but might be trying to repair the drive. 

I recommend stopping this process, as it can be lengthy and disruptive, and trying to enable external hard drive visibility. Here’s how:

1. Open Activity Monitor.
2. Search for a process called fsck_hfs.
3. Select it and click the X button in the top-left corner.

Now, check Disk Utility again — the drive may have appeared there. This solution may also work if your new hard drive is not showing up.

7. Force mount an external drive using the Terminal

Using the Terminal is another way to manually mount your hard drive. You can do it, even if you’ve never used the Terminal before. The key is to copy the instructions exactly as described — any extra or missing character or space will result in an error.

Here’s how to mount an external drive using the Terminal:

1. Connect the drive to a Mac.
2. Open the Terminal (you can find it using Spotlight).
3. Type the command: diskutil list. The Terminal will show you the list of available drives. Find the identifier of the disk you want to mount (e.g., disk2).
4. Insert the command to mount the disk: sudo diskutil mount /dev/disk2 (Replace disk2 with the identifier of your external drive).
5. Enter your password (no characters will appear on the screen — that's okay) and wait for the process to complete.

If the method described fails, you can try mounting the specific volume: sudo diskutil mount /dev/disk2s1. Remember to replace "disk2s1" with the name of your drive partition. 

If the drive won't mount anyway, check if it needs to be repaired: sudo diskutil repairDisk /dev/disk2.

8. Change the format of your hard drive

Many people who switch from PC to Mac don’t realize or forget (myself included when I made the switch) that these computers use different file formats. It could be that you are trying to connect something only fit to interact with Windows devices, such as NTFS. 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 on a Mac 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.

Mac not reading an external hard drive (or rather not writing to it) is normal in case you’re connecting an NTFS drive. The simple fix I can recommend in this case is to install iBoysoft NTFS for Mac, an app that unlocks read and write support for NTFS drives on Mac. 

If you’re dealing with some other unsupported drive format, you can try and change its format. 

Here's how to change the drive format:

1. Connect your external drive.
2. Open Disk Utility, select the drive, and click Erase.
3. Choose the right format under Format (APFS is standard for macOS) > Erase. 

9. Run First Aid

The most direct reason your external hard drive is detected 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. Select your external hard drive.
3. Access the First Aid tab, and click Run to start running diagnostics.

   

10. Reboot your Mac 

A hard disk not detected in a Mac can be a macOS issue. Hopefully, some data damage can be fixed by restarting your Mac. Go to the Apple menu > Restart. Or press and hold the power button, and when a dialog box appears, click Restart or press R. Rebooting your Mac essentially clears your macOS’s memory and starts it up fresh. 

11. Run Apple Diagnostics

If none of these solutions work, I recommend running Apple Diagnostics as a last resort. It will check for any Mac hardware issues and may provide a hint if something is interfering with the normal operation of your external drive.

To run Apple Diagnostics on Mac with the Silicon chip, follow these steps:

1. Disconnect all the devices from your Mac except for the essentials, such as a keyboard, monitor, mouse, etc.
2. Shut down your computer.
3. Start your Mac by pressing and holding the power button until you see the startup options.
4. Press Command + D  to run the Diagnostics test on your Mac.

If Apple Diagnostics finds problems, it will return you an error code. Find it in the list of reference codes and research the solution.

The diagnostic process is slightly different for Intel Macs. Check out our article on how to run diagnostics on a Mac for details and additional solutions.

How to recover data from a crashed drive

If you went through all the steps and weren’t able to fix the Mac not detecting an external hard drive, your drive is truly broken or formatted using a file system that the Mac cannot read. If the damaged drive contains data you can't afford to lose, I recommend trying to recover it with Disk Drill. It has saved me multiple times after I accidentally deleted important files and thought they were gone for good.

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. 

Here’s how to recover files with Disk Drill: 

1. Connect your drive to Mac.
2. Quit all other apps on Mac, especially those that may be trying to access the external hard drive (e.g. iPhoto, Words).
3. Open Disk Drill.
4. Click on the external drive from which you are trying to recover files. If it has partitions, you will see all of them. If, however, you still don’t see any volume on the external drive, you may need to try some of the steps above again or read the Disk Drill Scanning FAQs.
5. Scan the drive for lost files.
6. Preview the scan results, and once you’ve found the files you want to recover, click Recover.  

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

How to fix the external drive NTFS read-only problem 

External hard disk detected but not opening? As I’ve mentioned before, one common reason your Mac isn’t recognizing the external 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. The easiest fix I've ever tried for this issue is iBoysoft NTFS, an app that enables full read/write support for NTFS drives on Mac. 

A few more tips on getting your files back

Here are a few more tips that I believe can help you avoid similar problems in the future.

• 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, I'd 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.

  

• Partitions can get lost within hard drives, temporarily hiding all of the information contained within. Disk Drill can help identify and restore this information.
• 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.
• CleanMyMac, another useful app available from Setapp, can help you identify and repair external hard drive errors. It is an essential tool worth trying when you’re having external hard drive difficulties.

• A trick that can help you fix a hard drive not showing up on a Mac is to replace it with cloud storage. You can 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. To add cloud drives to Finder and  keep them close at hand, I use CloudMounter. I recommend you read detailed instructions on managing cloud storage as local drives . 

  

Summing up:  Tools to try if the external drive isn't recognized on a Mac

Hopefully, I’ve covered the topic, so you don’t have to google “external hard drive disappeared from the computer” ever again. Always start with the basics: properly eject the external device, check that the USB port is clean and the connection is secure, and ensure your operating system is up to date.

If these don’t solve the issue, try more specific solutions. 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 are all available via Setapp, an app subscription service that brings you 250+ apps for your tasks in one subscription.

FAQ

What to do when my external hard drive is not detected?

When your external hard drive is not detected, start with the basics: check the cable and port, see if the drive appears in Disk Utility, and restart your Mac. If that doesn't help, try running First Aid, resetting NVRAM, force-mounting the drive via Disk Utility or Terminal, or running Apple Diagnostics.