Fix Disk Utility First Aid Failed on APFS Volume in macOS

Symptoms

When running Disk Utility First Aid on an APFS volume in macOS, the process may fail with messages such as:

• "First Aid process has failed. Unable to repair volume."
• "The volume /dev/diskXsY could not be verified completely."
• "Error: -69845: File system verify or repair failed."
• "Operation timed out."

These failures can occur on internal SSDs, external drives, or Time Machine backups formatted as APFS.

Root Causes

Common causes include:

• APFS snapshot conflicts: macOS creates snapshots for Time Machine and system updates. First Aid may fail if snapshots are present.
• File system corruption: Unexpected shutdowns, disk errors, or bad sectors can corrupt APFS metadata.
• Insufficient permissions: Running First Aid from the user account without full disk access.
• Disk being mounted: Some APFS repairs require the volume to be unmounted or booted from Recovery.
• Third-party software: Utilities like Paragon or NTFS drivers may interfere.

Step-by-Step Fix

Step 1: Run First Aid from Recovery Mode

1. Restart your Mac and hold Command (⌘) + R until the Apple logo appears.
2. From macOS Utilities, select Disk Utility.
3. Select the APFS volume (e.g., "Macintosh HD") and click First Aid.
4. Click Run and wait for completion. If it fails, note the error code.

Step 2: Use Terminal in Recovery Mode

1. In Recovery Mode, go to Utilities > Terminal.
2. Type diskutil list to identify the disk identifier (e.g., disk1s5).
3. Unmount the volume: diskutil unmount force /dev/disk1s5
4. Run fsck_apfs: fsck_apfs -y -l /dev/disk1s5 or fsck_apfs -y /dev/disk1s5
5. If errors are found, run: fsck_apfs -y -d /dev/disk1s5
6. Repeat until no errors appear.

Step 3: Delete APFS Snapshots

1. In Terminal (Recovery Mode), list snapshots: diskutil apfs listSnapshots /dev/disk1s5
2. Delete each snapshot: diskutil apfs deleteSnapshot /dev/disk1s5 -name "snapshot_name"
3. Run First Aid again.

Step 4: Repair from Safe Mode

1. Restart and hold Shift until login window appears (Safe Mode).
2. Open Disk Utility and run First Aid on the APFS volume.

Alternative Fixes

• Use Disk Utility on a different Mac: Connect the drive to another Mac and run First Aid.
• Reset NVRAM/PRAM: Restart and hold Option + Command + P + R for 20 seconds.
• Repair with third-party tools: Consider DiskWarrior or Drive Genius for advanced repairs.
• Backup and reformat: If all else fails, back up data using cp or Time Machine, then reformat the disk as APFS.

Prevention

• Always eject external drives properly.
• Keep macOS and all software up to date.
• Run First Aid periodically (e.g., monthly).
• Avoid force-quitting during disk operations.
• Use a UPS to prevent power loss.
• Limit Time Machine snapshot retention if disk space is low.

By following these steps, you can resolve most Disk Utility First Aid failures on APFS volumes without data loss. If problems persist, contact Apple Support or visit an Apple Store.