How To Fix MAC Error nsDrvErr no such drive (tried to mount a bad drive num)


The nsDrvErr “no such drive” error is a common issue that Mac users face when trying to mount and access an external drive. This frustrating error indicates that your Mac is having trouble recognizing and mounting the external drive, making it inaccessible.

This issue can occur for a variety of reasons – the drive may be corrupted, disconnected improperly, or there may be an issue with the USB port or cable. Thankfully, there are several troubleshooting steps you can take to resolve this error and regain access to your important files stored on the external drive.

In this guide, we’ll walk through the top solutions for fixing the nsDrvErr “no such drive” error on your Mac. Follow along step-by-step to troubleshoot the issue and learn how to successfully mount and access your external drive again.

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What Causes the nsDrvErr no such drive Error?

Before jumping into the solutions, let’s first understand what causes the nsDrvErr “no such drive” error in the first place. There are a few common culprits:

  • Faulty or loose cable connection – If the USB or Thunderbolt cable connecting your external drive to your Mac is loose or faulty, it can prevent your Mac from detecting the drive.
  • Drive formatting issues – If your external drive is formatted incorrectly or corrupted, your Mac may not recognize it. Common formatting problems include using an incompatible file system or a corrupted disk.
  • Drive failure – If the external drive has failed or is damaged, it won’t properly connect and mount to your Mac. Signs of failure include strange noises, disappearing data and read/write issues.
  • OS issues – Corrupted system files, permissions issues, and software conflicts can also prevent your Mac from detecting external drives.
  • Bad USB port – Damaged or malfunctioning USB ports on your Mac are another possible cause. Trying different ports can help isolate this issue.

Knowing what causes the problem helps you pinpoint where to focus your troubleshooting. Now let’s go through the top solutions to fix the no such drive error.

1. Check Cable Connections

The first step is the easiest – check whether the USB or Thunderbolt cable connecting the drive to your Mac has come loose or disconnected.

If it has, firmly reconnect the cable at both ends to ensure a snug fit. Use a different high-quality cable if available. Damaged or faulty cables are a common reason for external drive connection issues.

After reconnecting the cable, check if the drive shows up and mounts successfully on your Mac. If the connection seems fine but the drive still won’t mount, move on to the next solutions.

2. Try Different USB Ports

If you’ve verified the cable is not the issue, try plugging the drive into different USB ports on your Mac.

Using another port can help determine if the original USB port is damaged or malfunctioning, preventing your Mac from properly communicating with the drive.

Make sure to try every available USB port, both on the side and back of your Mac. Also test USB ports on both sides if you have a MacBook Pro or MacBook Air.

If the drive mounts successfully in some ports but not others, the problem lies with your Mac’s USB ports. If it fails to mount across all ports, the drive itself likely has an issue.

3. Reboot Your Mac

An easy but often effective solution is restarting your Mac. Rebooting can clear any software glitches and refresh the connection between your Mac and the external drive.

To reboot, first safely eject and disconnect the external drive if currently connected. Then power off your Mac completely rather than just logging out.

After 30 seconds, power your Mac back on and reconnect the external drive once the system has fully loaded. The drive should hopefully mount successfully after this refresh.

If a reboot doesn’t help, don’t fret – there are still several troubleshooting steps to try.

4. Run First Aid on the Drive

Using Mac’s built-in Disk Utility program, you can check the external drive for errors and attempt to repair them.

Disk Utility can resolve any disk corruption or file system problems that may be preventing your Mac from recognizing the drive. Here’s how to run First Aid:

  1. Open Disk Utility (located in Applications > Utilities)
  2. Select your external drive on the left side
  3. Click First Aid in the top center and then click Run
  4. Allow First Aid to scan the drive – this may take a few minutes
  5. When complete, you can view the First Aid report with any found errors
  6. Repeat if needed until no errors are found

This should resolve any minor disk problems. If major issues are found, you may need to reformat the drive (more on this below).

5. Reformat the External Drive

For persistent mount issues or a failing drive, reformatting can give your drive a fresh start. But note this will erase all data on the drive, so first try to backup any needed files.

Here are the steps to reformat in Disk Utility:

  1. Open Disk Utility
  2. Select your external drive
  3. Click Erase in the top center
  4. Choose a reformatting scheme – APFS is optimal for most drives
  5. Rename the drive if desired
  6. Click Erase

Once completed, your drive will be blank and ready to use. Any underlying disk errors should be cleared. Reconnect the drive and see if it now mounts successfully.

6. Update Your Mac’s Software

Outdated software can sometimes cause peripheral devices like external drives to malfunction.

Updating your Mac’s operating system, apps, and any related software to the latest versions can help resolve conflicts.

To update your system software, open the App Store app and click Updates. Install any macOS updates available. Keeping your system up-to-date is a good maintenance habit for optimal performance.

For app updates, simply launch each installed app periodically and check for new versions available. Keeping apps updated can fix bugs that affect connectivity.

7. Try Mounting the Drive on Another Mac

To better isolate where the issue lies, attempt mounting and accessing the drive from another Mac.

Borrow a friend or family member’s Mac and connect your drive. If the drive mounts fine on their system, the issue likely lies with your Mac. But if it still fails to mount, the drive itself has problems.

This quick test can identify if the problem is tied to your specific machine and narrow down where to focus your troubleshooting.

8. Contact Apple Support

If you still can’t get the drive to mount after trying all troubleshooting steps, reach out to Apple Support for personalized help.

You can contact Apple Support by phone, chat, email, or scheduling an appointment at an Apple Store’s Genius Bar. An Apple expert can assist with advanced troubleshooting tailored to your situation.

Providing them with details on the issue, your Mac model, and troubleshooting already attempted will help them provide relevant solutions. Their specialized knowledge may pinpoint less obvious causes.

9. Try Data Recovery Software

If no solutions have worked and you absolutely need to access the data on the drive, third party data recovery software provides one last option.

Recovery software bypasses any mount issues and pulls data directly off the storage media. Advanced programs can recover data even from crashed or corrupted drives.

However, this is an expensive solution only warranted if the data is highly valuable and irreplaceable. Also research the software thoroughly, as some options are more effective than others.

10. Send for Professional Data Recovery

For highest success with a severely damaged or failed drive, a professional data recovery service may be able to salvage your data.

Reputable recovery experts possess specialized tools and clean room facilities to repair drives and extract data at the component level.

This is the most reliable but also most costly method. Only pursue professional recovery for truly critical and irreplaceable data due to the high price.


The nsDrvErr “no such drive” error can certainly be frustrating, but thankfully this guide has outlined the top solutions for getting your external drive recognized again on Mac.

Start by checking connections and trying different ports, then utilize tools like First Aid and reformatting to repair any disk errors. Updating your system, verifying the issue on another Mac, and contacting Apple provide additional troubleshooting avenues.

And if all else fails,Error nsDrvErr recovery software and professional data recovery services offer last resort options for accessing your important data.

Persevering methodically through these troubleshooting steps should resolve your no such drive problems, allowing you to once again access all the data on your external drive. Don’t give up hope – solutions exist to defeat this error!

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