Summary: This content is about Disk Utility First Aid on your Mac. It includes how to use First Aid, how to run First Aid from macOS Recovery mode, and what to do if Disk Utility First Aid fails or is not working on your Mac.
Disk Utility First Aid is a built-in disk repair software in macOS. Its main task is to verify and check the health of the disks and volumes on your Mac, such as Macintosh HD, SSD, external hard drives, USB drives, flash drives, and SD cards.
If necessary, First Aid is able to repair minor errors in disk file system and partition structure, which cuts the loss before the disk gets more serious corruption.
How to run First Aid to repair the disk on your Mac?
When your Macintosh HD and external drives are not working, unreadable, corrupted, or unmountable, or your Mac won't turn on, you can use First Aid to check if there is a problem inside the disk.
Step 1: Open Finder, go to the Applications folder, Utilities folder, find Disk Utility and open it.
If the problematical disk is Macintosh HD, you need to repair it in macOS recovery mode. Please hold Command + R and start your Mac into macOS Recovery mode. Then you can select Disk Utility from macOS Utilities window and click Continue.
Step 2: Click on View and choose Show All Devices to list all detected disks and volumes.
Step 3: Select the drive or volume that you want to repair in the left sidebar.
Step 4: Click First Aid on the top menu of Disk Utility.
Step 5: Click Run to check and repair errors in this drive.
If Disk Utility reports that the operation successful or has been repaired, you're done. Check if you can access that disk.
If Disk Utility First Aid process has failed, you can expand "Show Details" and see the detailed error code and message as below:
- Invalid node structure
- Invalid B tree node size
- APFS object map is invalid
- APFS fsroot tree is invalid
- File system check exit code is 8
- Invalid volume directory file count
After Disk Utility can't repair the disk, it's asking if possible back up the data on this volume.
Disk Utility First Aid failed to repair the disk, what to do?
If you receive a report that Disk Utility First Aid process has failed or Disk Utility First Aid can't repair the found errors, you'd better back up your data as much as possible. There are several solutions you can have a try to back up the data:
1. Back up the data with macOS built-in Time Machine.
2. Recover data with iBoysoft Data Recovery for Mac.
- How to recover data from Mac that won't turn on?
- How to run iBoysoft Data Recovery for Mac in macOS Recovery mode?
3. A local data recovery specialist.
After backing up the data, you can erase this drive with Disk Utility and make the external drive working again, or reinstall macOS on the Macintosh HD.