6 Methods to Fix External Hard Drive Not Mounting on macOS Tahoe 26

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An external hard drive that won't mount on macOS Tahoe 26 can instantly disrupt your workflow - especially if it contains important files, backups, or creative work. While macOS is known for its robust disk management, mounting issues can arise due to hardware malfunctions, software incompatibilities, or file system corruption.

In this guide, we'll walk you through a comprehensive series of steps - from basic checks to advanced recovery tools - to help you diagnose the problem and get your external drive working again on macOS Tahoe 26.

Why External Drives Fail to Mount on macOS Tahoe 26?

macOS "mounts" external storage when it recognizes and assigns it a location in Finder, enabling you to interact with it. If your external hard drive doesn't mount, you may be facing one of the following:

• Faulty USB cables or ports
• Power issues with the drive
• File system errors or corruption
• Format incompatibility (e.g., NTFS on macOS)
• Software bugs or permission changes in macOS Tahoe 26

Basic Checks Before Diving Deep

Before you go into disk repair or Terminal commands, it's best to rule out common physical issues:

1. Try Different USB Ports and Cables

• Connect the drive to another USB port.
• Swap the cable with a known working one.
• If using a USB-C hub or adapter, try a direct port or different hub.

2. Test the Drive on Another Computer

• Plug the drive into a different Mac or even a Windows PC.
• If it shows up elsewhere, the issue may be macOS-specific.

3. Check Drive Power Supply

• Some 3.5-inch drives require an external power source. Ensure the adapter is connected and functional.

Recover Files from Unmounted External Hard Drive on macOS Tahoe 26

It is highly recommended to back up or recover files before fixing external hard drive not mounting on macOS Tahoe 26. If you can't manually copy files from the external hard drive to another drive, you can use Mac data recovery software - such as Donemax Data Recovery for Mac to recover the files.

Step 1. Download and install Donemax Data Recovery for Mac and connect the external hard drive to the same Mac.

Step 2. Open Donemax Data Recovery for Mac, then select the external hard drive to start data recovery.

Step 3. Click on Scan button to deeply scan the external hard drive and find all recoverable files including existing files, inaccessible files, deleted files, formatted/lost files, etc.

Step 4. After scanning, you can preview all recoverable files. Then select the wanted files, click on Recover button. Choose a safe location to save the recovered files.

Donemax Data Recovery for Mac also can help:

• Recover permanently deleted files from the external hard drive.
• Recover lost files from an formatted external hard drive.
• Repair corrupted external hard drive on Mac.

6 Methods to Fix External Hard Drive Not Mounting on macOS Tahoe 26

Fix 1. Check Disk Utility for Drive Visibility

Disk Utility is your first stop in macOS to inspect connected disks:

Steps to Access Disk Utility:

• Go to Finder > Applications > Utilities > Disk Utility.

• Check the sidebar for your external drive.

Scenarios:

• Drive shows but is grayed out: It's detected but unmounted - try selecting it and clicking "Mount".

• Drive doesn't appear: Proceed to Terminal or hardware diagnostics.

Fix 2. Run First Aid in Disk Utility

Disk Utility includes a First Aid tool to check and repair file system issues.

Steps:

1. Open Disk Utility and select the external drive.
2. Click First Aid and confirm.

3. Wait for the check to complete.

Interpretation:

• "The volume appears to be OK" → likely a mount permission issue.
• "Errors found and repaired" → retry mounting.
• "Cannot repair the disk" → may require data recovery or reformat.

Fix 3. Use Terminal to Manually Mount the Drive

While Disk Utility offers a graphical interface for managing drives, it may not always detect or mount problematic volumes - especially if the drive has file system inconsistencies or macOS doesn't assign it a mount point automatically. In such cases, macOS Terminal becomes an essential tool for advanced troubleshooting.

Here's how to use Terminal to manually inspect and attempt to mount an external hard drive on macOS Tahoe 26.

1. View Disk List

Open Terminal and type:

diskutil list

Identify your external drive by size or label (e.g., /dev/disk5).

2. Mount the Drive Manually

diskutil mount /dev/diskX

(Replace diskX with your drive's actual identifier)

If it mounts successfully, it should appear in Finder.

3. Repair via Terminal

You can also attempt a repair:

diskutil repairVolume /dev/diskX

4. Try Forcing the Mount Process (Advanced)

If mounting with diskutil doesn't work, you can try mounting manually by creating a mount point:

1. Create a mount directory:

   sudo mkdir /Volumes/MyExternalDrive

2. Mount the drive manually (assuming it's formatted as HFS+):

   sudo mount -t hfs /dev/disk2s1 /Volumes/MyExternalDrive

💡 Note: Replace hfs with the appropriate file system type:

• apfs for APFS-formatted drives
• msdos for FAT32
• exfat for exFAT
• ntfs (requires additional drivers for write support)

If successful, the disk will be accessible via the specified folder.

5. Unmount and Remount the Drive

Sometimes unmounting and remounting helps resolve stuck volumes:

sudo diskutil unmountDisk /dev/disk5
sudo diskutil mountDisk /dev/disk5

• unmountDisk detaches all volumes on the physical disk
• mountDisk attempts to reinitialize and mount all available partitions

This is especially useful when macOS has inconsistently mounted partitions.

6. View System Log for Mounting Errors

To troubleshoot further, you can check macOS logs for mounting errors:

log show --predicate 'eventMessage contains "disk"' --info --last 1h

Look for messages such as:

• "Disk arbitration failed"
• "Could not mount disk because…"

  These can point you toward file system corruption, driver conflicts, or kernel permission issues.

Fix 4. Check Finder Settings

Your drive might be mounted but not visible in Finder due to settings.

Steps:

1. Open Finder > Settings (Preferences).

2. Go to the Sidebar tab and ensure External Disks is checked.

3. Also check "External disks" under the General tab to make it show on the desktop.

Fix 5. Address Known Issues in macOS Tahoe 26

macOS Tahoe 26 has introduced several new privacy and USB device handling updates that could interfere with drive mounting.

1. Update macOS

Go to System Settings > General > Software Update

Install any pending updates or security patches.

2. Reset SMC and NVRAM

Sometimes, resetting system memory helps resolve I/O and USB issues.

To reset NVRAM:

1. Turn off your Mac.
2. Turn it on and immediately press and hold: Option + Command + P + R
3. Hold for ~20 seconds, then release.

To reset SMC (for Intel Macs):

• Shut down > Hold Shift + Control + Option + Power for 10 seconds > Release and power on.

💡 Note: Apple Silicon Macs reset SMC automatically on reboot.

Fix 6. Check and Change Drive Format

If your drive is using NTFS, macOS can read but not write or mount it in some cases.

How to Check Format:

• Open Disk Utility.
• Click on the external drive and look the file system (e.g., NTFS, exFAT, HFS+).

Solutions:

Solution 1. Use NTFS drivers for Mac (e.g., Donemax NTFS for Mac)

Step 1. Download and install Donemax NTFS for Mac.

Step 2. Open Donemax NTFS for Mac, select the NTFS external hard drive, click on Mount button.

Step 3. Click on Enable Writable button so that you can write data to any NTFS drive on macOS Tahoe 26.

Solution 2. Reformat the drive to a macOS-compatible format (APFS, ExFAT, or Mac OS Extended)

Steps to Reformat:

1. Select the drive in Disk Utility.
2. Click Erase.

3. Choose format (ExFAT for cross-platform, APFS for macOS only).

4. Confirm.

When to Contact a Data Recovery Professional

If the drive doesn't appear at all in Disk Utility or Terminal, and you hear clicking, grinding, or if the drive overheats:

Signs of Physical Failure:

• No LED or power indication
• Repetitive clicking sounds (head crash)
• Smell of burning or overheating

Next Steps:

• Avoid DIY recovery to prevent further damage.
• Contact professional services like:
  • DriveSavers
  • Ontrack
  • Gillware

They can often retrieve data from dead drives using cleanroom technology.

Prevent Mounting Issues in the Future on macOS Tahoe

Now that your external drive is accessible again - or replaced - it's wise to follow best practices to avoid mounting issues in the future.

Tips:

• Eject safely using Finder or right-click
• Use macOS-compatible formats (APFS, exFAT)
• Avoid using the drive across multiple OSes without proper format support
• Back up regularly using Time Machine or cloud services
• Keep macOS updated for driver and security patches

Conclusion

When an external hard drive won't mount on macOS Tahoe 26, the problem can range from minor software bugs to serious file system corruption or hardware failure. By following this structured guide - from checking hardware to using Disk Utility, Terminal, or third-party recovery tools - you can resolve most mounting problems without losing data.

If all else fails, professional recovery remains a viable last resort. Always back up important files, and ensure your drives are ejected and formatted correctly to maintain their health and longevity on macOS.

FAQs About Repairing and Mounting External Hard Drive on macOS Tahoe 26

1. How to mount an external hard drive on macOS Tahoe 26?

Follow the steps below to mount an external hard drive on macOS Tahoe 26:

• Open Disk Utility, select the drive that is unmounted.
• Click on Mount button.
• If the Mount button is grayed out, click on First Aid button to repair the drive.

2. How to use third-Party tools for macOS Tahoe 26 drive mounting issues?

If the native tools don't help, these utilities may offer advanced mounting or repair options:

🔹 Donemax NTFS for Mac

100% safe, powerful and easy-to-use tool to help mount any drive including NTFS drive on macOS Tahoe 26 and can repair corrupted drive, reformat RAW drive, etc.

🔹 FUSE for macOS

An open-source utility to support different file systems. Requires technical setup but supports NTFS and EXT drives.

🔹 DiskWarrior

Repairs corrupted directories that prevent mounting.

🔹 Paragon or Tuxera NTFS

Best for users needing NTFS write and mount support on Mac.

🔹 Mounty for NTFS

Free, lightweight tool that mounts NTFS volumes with write access.

3. How to recover data from unmounted drives on macOS Tahoe 26?

If the drive is visible but refuses to mount or has corrupted file systems, consider data recovery before formatting.

Top Recovery Tools:

Donemax Data Recovery for Mac

• Detects unmounted or RAW drives
• Supports NTFS, HFS, APFS, FAT32, exFAT
• Can preview files before recovery

EaseUS Data Recovery Wizard

• Easy interface
• Deep and quick scan options
• Ideal for drives that are detected but won’t open

Stellar Data Recovery

• Supports various file systems and file types
• Offers a disk image creation feature

Steps:

• Install your chosen tool.
• Select the unmounted drive.
• Run the scan and preview files.
• Recover and save to a different destination.

4. Can I use NTFS drive on macOS Tahoe 26 without formatting?

Yes, third-party NTFS driver - such as Donemax NTFS for Mac is fully compatible with macOS Tahoe 26. It can quickly mount NTFS drive on macOS Tahoe 26 and add NTFS read-write support to the Mac.