External Hard Drive Not Showing Up on Mac: What To Do

One of the most frustrating situations that can arise for any Mac user is when the system does not recognize an external hard drive. This issue can stem from various causes, including connectivity problems, incompatible file formats, and even the presence of malware. It’s a common problem that can occur even with brand-new devices.

Fortunately, the majority of these issues can be resolved through quick and easy troubleshooting steps. In this comprehensive guide, we’ll walk you through the most effective solutions to get your external hard drive properly recognized and functioning on your Mac once again.

Why is your Mac not detecting your external hard drive?

There are several common reasons why your Mac may not recognize your external hard drive. Understanding the potential causes can help you identify the issue and better troubleshoot the problem.

Issue: Incompatible file format

An incompatible file system format is one of the most frequent culprits for Macs not recognizing external hard drives. Macs and Windows PCs use different file systems, which can lead to compatibility problems. If your external hard drive is formatted in a Windows-centric file format like NTFS, your Mac may not be able to read or access the drive’s contents.

Compatible file formats with macOS are: 

• APFS (Apple File System) is the default format for Mac. This is the preferred format if you’ll use your external HD only on macOS.
• macOS Journaled is a specific format for macOS that you can use if you don’t need your files to be encrypted.
• macOS Extended encrypts your files and requires a password. It’s also known as HFS+ (Hierarchical File System Plus)
• exFAT is a file format compatible with Windows and macOS and is recommended for users who connect their external hard drives to both systems. 

How to fix: Check the file format

Use Disk Utility to see what file format your external hard drive uses. If it’s incompatible with macOS, you must reformat the drive. Back up any important data first, as reformatting will erase everything on the drive.

1. Turn on your Mac or MacBook and go to Finder > Go > Utilities > Disk Utility.
2. Then, select the disk you want to format from the menu at the left. It will probably be named Macintosh.
3. Click Erase to format the drive.
4. Choose the file system and confirm the format of the drive.

Issue: Corrupted or damaged drive

Another common reason Macs do not recognize external hard drives is that the data on the drive has become corrupted or that the drive itself is physically damaged. When the file system or drive components are compromised, your Mac may not communicate properly with or mount the external storage device.

How to fix: Reset the NVRAM

While your Mac’s NVRAM (non-volatile random-access memory) isn’t directly involved in recognizing external hard drives, resetting it can sometimes fix issues with external drive recognition. 

1. Shut down your Mac, then hold down Command + Option + P + R at startup.
2. Hold the keys for about 20 seconds. This ensures the NVRAM reset is complete.
3. Release the keys and let your Mac boot up normally.

Issue: Power supply issues

Some larger or high-capacity external hard drives require more power than a standard USB port can reliably provide. If the drive isn’t getting enough power, your Mac may fail to recognize it as a valid, functional storage device.

How to fix: Run Disk Utility’s First Aid

Disk Utility’s First Aid feature can check for and repair any issues with the drive’s file system. Run First Aid to see if it can resolve the problem.            

1. Go to Applications > Utilities > Disk Utility.
2. In Disk Utility, look for your external hard drive in the sidebar. 
3. Once you locate your external drive, select it from the sidebar. 
4. Then, click the First Aid button at the top of the Disk Utility window.
5. A dialog box will appear. Click Run to start the First Aid process. This will check the disk for errors and attempt to repair them.
6. After First Aid is complete, review the results presented in Disk Utility. This will inform you if any issues were found and whether they were repaired successfully. 

If errors were detected but not fixed, consider re-running First Aid or exploring further troubleshooting options.

1. Restart your Mac to refresh its system settings. 

If the drive still does not appear after running First Aid and checking connections, consider other troubleshooting methods, such as resetting the System Management Controller (SMC) or testing the drive on another computer.

Issue: Connectivity problems

Issues with the USB connection can also prevent your Mac from detecting the external drive. A loose, damaged, or faulty USB cable can disrupt the communication between your Mac and the external storage.

How to fix: Try a different USB port or cable

Plug the external hard drive into a different USB port on your Mac, and try using a different USB cable. This can help isolate whether the issue is with the port, the cable, or the drive itself.

Issue: macOS settings

Problems with your Mac’s system settings, such as Finder preferences or security permissions, can sometimes interfere with recognizing external drives. Improper configurations in these areas may prevent the Mac from overlooking or denying access to the connected hard drive.

How to fix: Change Finder preferences and update your macOS

Keeping your macOS up to date can help resolve compatibility issues and fix any bugs causing the external drive recognition problem. But, if the issue is because of Finder preferences, you can easily change it on the program itself.

Changing Finder preferences:

1. Click on the Finder icon in the Dock (the smiley face icon).
2. In the top menu bar, click on Finder, then select Settings (or Preferences, depending on your macOS version) from the dropdown menu.
3. In the General tab, ensure that the option “Show these items on the desktop” includes External disks. When connected, this will allow your external hard drive to appear on your desktop.
4. Click on the Sidebar tab and check External disks under the Devices section. This will ensure that your external hard drive is visible in the Finder sidebar for easy access. 

Updating macOS

1. Click the Apple logo in the top left corner of your screen and select System Preferences.
2. Then, click on Software Update. Your Mac will check for available updates.
3. If updates are available, click on Update Now.
4. Follow any prompts to complete the installation process.
5. Restart your Mac (if required)

When to seek professional help?

If you’ve exhausted all of these troubleshooting options and your external hard drive is still not showing up, it may be time to seek professional data recovery assistance. The hard drive data recovery experts at SalvageData Canada can help retrieve your important files, even from a severely damaged or undetected hard drive.