There are a few common reasons why an external disk drive may not show up on a Mac computer. Here are some quick troubleshooting tips to try:
Check Basic Connections
First, check that the USB or Thunderbolt cable connecting the external drive to your Mac is firmly plugged in at both ends. Loose connections can prevent the drive from being detected. If it’s a USB drive, try plugging it into another USB port on your Mac to rule out a bad port.
Check For Physical Damage
Inspect the external drive for any signs of physical damage or faulty hardware. Listen and feel if the drive is making any unusual noises when connected as this can indicate a problem with the drive itself. If it seems like a hardware issue, you may need to replace the drive.
Restart Your Mac
Restart your Mac to reset the operating system and hardware. After rebooting, reconnect the external drive. Often a simple restart will resolve any software glitches preventing detection of the external drive.
Check Disk Utility
Open Disk Utility on your Mac (located in Applications > Utilities). Check if the external drive shows up here but not in Finder. If you see the drive in Disk Utility, try mounting it by selecting the volume and clicking “Mount” in the top menu.
Change Finder Settings
Go to Finder > Preferences and make sure the “External disks” option is checked under “Show these items on the desktop.” This should make any connected external drives show up on the desktop.
Reset NVRAM
Resetting NVRAM can help fix USB and disk drive connectivity issues. To reset NVRAM, restart your Mac and hold down Command + Option + P + R keys together until you hear the startup chime again. Then let go and let your Mac restart normally.
Change USB Ports or Cables
If you have other USB devices or cables available, try connecting the external drive using a different USB port or cable. A faulty USB port or cable could prevent the drive being detected properly.
Check System Information
Open System Information via About This Mac > System Report and check if the external drive shows up under Hardware > USB or Thunderbolt. If not, the issue is with OS detection, not hardware.
Update macOS
Make sure your Mac is running the latest version of macOS. Go to System Preferences > Software Update and install any available updates, which may resolve compatibility issues.
Check Energy Saver Settings
Go to System Preferences > Energy Saver and check the settings. Some drives may not show up if computer has gone to sleep. Change settings to prevent your Mac from sleeping when the drive is connected.
Check Disk Drivers
External drives may require additional drivers to work properly on a Mac. Check the manufacturer’s website for any Mac-specific drivers available for the external drive model and install if needed.
Try Another Computer
Connect the external drive to another computer or laptop running Mac OS to see if the drive shows up there. If it doesn’t, there is likely an issue with the drive itself.
Check or Repair Disk Format
Open Disk Utility and check if the external drive has the correct formatting for Mac such as HFS+, APFS, or exFAT. If incorrectly formatted, you can try reformatting the drive.
Verify or Repair Disk Issues
Use First Aid in Disk Utility to check for and repair any disk errors that could be preventing the external drive from appearing.
Force Mount the Drive
If you know the exact disk path, you can try forcing the drive to mount by opening Terminal and running a command like “mount -t apfs /dev/disk2s2” (replace with your own disk path).
Reset SMC
For Macs with T2 security chips, an SMC reset can resolve hardware issues like external drives not appearing. Power off your Mac and press Shift + Control + Option keys and the power button together.
Troubleshoot Finder Issues
Trashing Finder preferences may resolve Finder-specific issues that could prevent external drives showing up properly. Hold Option key and right-click on the Finder icon in the Dock and select “Relaunch.”
Use Disk Singer Tool
Third party utilities like Disk Singer can force stubborn disk drives to mount. Download, install, and run the tool to see if it can make your external drive show up.
Reinstall macOS
A clean reinstall of your Mac’s operating system software can clear out any bugs or glitches that may be preventing proper external drive detection and access.
Replace USB or Thunderbolt Cable
Faulty or damaged cables are a common cause of drives not appearing properly. Swap the cable with a known working one to determine if the cable is faulty.
Check for Conflicts
USB or Thunderbolt conflicts between devices can prevent proper drive detection. Unplug other devices to see if the drive shows up then. Update drivers for the conflicting devices.
Conclusion
In summary, there are many potential fixes if an external hard drive or disk is not showing up on your Mac. Some common things to try include restarting the Mac, checking connections, resetting NVRAM, updating macOS, trying different ports and cables, reformatting the drive if necessary, and ruling out any conflicts with other devices. Resetting SMC or reinstalling macOS may help for stubborn problems. Overall, following methodical troubleshooting steps will help identify and resolve the issue.
Troubleshooting Table
| Issue | Solution |
|---|---|
| Loose cable connection | Check cable connections at both ends |
| Damaged drive hardware | Inspect drive for damage, unusual noises |
| Software glitches | Restart Mac, reset NVRAM |
| Finder settings issue | Check Finder preferences |
| macOS compatibility | Update to latest macOS |
| Sleep settings conflict | Adjust Energy Saver settings |
| Incorrect disk format | Reformat drive if needed |
| Disk errors | Run First Aid to check/repair disk |
| Hardware conflicts | Unplug/update other devices |
| Faulty cable | Replace USB or Thunderbolt cable |