How to Fix “The Disk You Inserted Was Not Readable by This Computer” on Mac
Solve the common Mac issue of unreadable external disks with steps like checking hardware connections, using Disk Utility’s First Aid, recovering data before formatting, or advanced Terminal commands. Causes include hardware problems, file system incompatibility, or corrupted disks. Always consider data recovery software before reformatting.
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Key Takeaways
- The error “The Disk You Inserted Was Not Readable by This Computer” on Mac can often be resolved with basic troubleshooting steps.
- Causes range from hardware issues and incompatible file systems to corrupted disks.
- Tools like Disk Utility, Terminal, and third-party data recovery software can help resolve the issue.
- Formatting the disk is a last resort if repairing fails, as it erases all existing data.
- Affiliate Tip: Consider using reputable data recovery software before reformatting to minimize data loss.
Step-by-Step Guide to Fix “The Disk You Inserted Was Not Readable by This Computer” on Mac
Step 1: Basic Troubleshooting
-
Check Connections:
- Ensure the external disk is firmly connected to your Mac.
- Examine the cable and ports for signs of physical damage.
- Test the disk with a different cable or USB port.
-
Reboot Your Mac:
- Restarting the system can often resolve minor software conflicts that may prevent the disk from being read.
- Disconnect the disk before rebooting, then reconnect it once macOS restarts.
-
Verify on Another Computer:
- Check if the disk can be accessed from another Mac or Windows device to rule out hardware failure.
Step 2: Run First Aid in Disk Utility
Disk Utility’s First Aid function automatically attempts to repair disk corruption.
-
Open Disk Utility:
- Navigate to
Applications > Utilities > Disk Utility
.
- Navigate to
-
Select the Disk:
- On the left sidebar, locate the unreadable disk. If it doesn’t appear, click View > Show All Devices.
-
Run First Aid:
- Select the unreadable disk.
- Click the First Aid button in the top menu.
- Follow the on-screen prompts to repair errors.
Expert Tip: If First Aid fails, take note of any error messages. These often indicate whether the issue is hardware-related or software-related.
Step 3: Unmount and Remount the Disk
Sometimes the macOS Finder fails to properly mount the disk. Re-mounting might restore access.
- Return to Disk Utility.
- Select the disk.
- Click Unmount, wait a few seconds, and then click Mount again.
Step 4: Investigate File System Compatibility
If the disk was formatted on another platform, its file system may not be recognizable by macOS.
- Open Disk Utility and select the disk.
- Check the Format under the disk name:
- APFS & HFS+: Supported by macOS.
- FAT32 or ExFAT: Used for cross-platform compatibility.
- NTFS: Read-only support on macOS; requires a third-party driver (e.g., Paragon NTFS for Mac).
Solution: If the file system is incompatible, backup data using third-party software, then reformat the disk to macOS-compatible file systems: APFS or HFS+.
Step 5: Recover Data Before Formatting
If none of the above steps resolve the issue, it’s highly likely the disk is corrupted. Recover your files before reformatting.
-
Install Data Recovery Software (Affiliate Links):
-
Launch the tool and connect your problematic disk.
-
Scan the Disk:
- Use the recovery software to scan the disk for deleted or damaged files.
- Recover and Save:
- Preview the recoverable files, and save them to a different device (e.g., your internal SSD).
Expert Advice: Avoid writing new data onto the corrupted disk before using recovery software. This maximizes the chances of successful data retrieval.
Step 6: Format the Disk (Last Resort)
If the problem persists, you’ll need to erase and reformat the disk to restore functionality. Note that this will delete all data on the drive.
-
Open Disk Utility.
-
Select the Disk and Click Erase.
-
Choose File System:
- For macOS: Use APFS or HFS+.
- Cross-Platform: Select ExFAT (for compatibility with Windows).
-
Name your drive and click Erase.
Affiliate Suggestion: Use MiniTool Partition Wizard to perform advanced formatting tasks efficiently.
Step 7: Use Terminal for Advanced Repairs
Advanced users can leverage macOS Terminal to manage disks via commands.
- Open Terminal (Applications > Utilities > Terminal).
- Run
diskutil list
to see all available disks. - Try commands like:
diskutil verifyDisk /dev/diskX
(ReplaceX
with your disk ID) to check for errors.diskutil repairDisk /dev/diskX
to attempt repairs.
Caution: Terminal commands can overwrite data. Double-check inputs to avoid accidental loss.
Additional Tips
- Use AdGuard to prevent disruptive ads while downloading recovery or repair tools.
- Reset the System Management Controller (SMC) if USB devices aren’t recognized. Check Apple’s official guide for instructions.
- Keep your Mac updated to ensure compatibility with external drives.
Frequently Asked Questions
1. Why is my external hard drive unreadable on my Mac?
Your disk may have a corrupted file system, incompatible formatting, or hardware damage.
2. Can I recover files from an unreadable disk?
Yes. Use tools like Wondershare Recoverit or Disk Drill to retrieve lost data before formatting.
3. What file system should I use for formatting an external drive on Mac?
- APFS or HFS+: For exclusive macOS use.
- ExFAT: For compatibility with both Mac and Windows.
4. Should I replace the disk if formatting fails?
If hardware diagnostics suggest physical damage, replacing is the only option. However, confirm this by testing on another device.
5. Can I prevent this issue in the future?
Yes:
- Regularly back up your data using Time Machine.
- Eject disks properly before unplugging them.
Affiliate Tip: Using tools like MacBooster helps keep your macOS optimized and less prone to such issues.