Software⏱️ 3 min read📅 2026-06-19

How to Fix: External disk repair error on a MacBook Pro

External disk repair error on a MacBook Pro - Time Machine issue

Quick Answer: Try resetting the Time Machine backup by erasing the backup and then re-enabling it.

📋 Table of Contents

  1. 🔍 Why This Happens
  2. 🔧 Proven Troubleshooting Steps
  3. 💡 Conclusion

The error 'Could not unmount Disk' on a MacBook Pro with an external WD Passport drive is frustrating, especially when trying to access backed-up files. This issue can occur due to various reasons such as disk corruption, file system errors, or issues with the Time Machine software.

In this guide, we will walk you through the steps to troubleshoot and potentially fix this error, allowing you to regain access to your backed-up files.

🔍 Why This Happens

  • The primary reason for this error is disk corruption. When a file system becomes corrupted, it can cause issues with disk mounting, leading to the 'Could not unmount Disk' error.
  • Another possible reason could be a problem with the Time Machine software or its configuration.

🔧 Proven Troubleshooting Steps

Disk Utility Repair

  1. Step 1: Step 1: Open Disk Utility on your MacBook Pro. You can find it in the Applications/Utilities folder, or use Spotlight to search for it.
  2. Step 2: Step 2: Select the external WD Passport drive from the list of available disks. Make sure it's the correct disk and not a different one.
  3. Step 3: Step 3: Click the 'First Aid' tab on the top menu bar and click the 'Run' button next to it. Disk Utility will scan the disk for errors and attempt to repair them. This process may take several minutes, depending on the size of the drive.

Time Machine Repair

  1. Step 1: Step 1: Go to the Apple menu and select 'Restart' to restart your MacBook Pro.
  2. Step 2: Step 2: Immediately hold down the 'Command + R' keys while booting up. This will take you to the macOS Recovery Mode.
  3. Step 3: Step 3: In the Recovery Mode, select the language and click on 'Continue'. Then, select the 'Disk Utility' app from the Utilities menu and follow steps 1-3 in Method 1 above.

💡 Conclusion

If the issue persists after trying both methods, it may be worth considering reformatting or replacing the external WD Passport drive. However, if you're able to successfully repair the disk using Disk Utility or Time Machine Repair, you should regain access to your backed-up files.

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