How to Run First Aid in Disk Utility on Mac

First Aid is Disk Utility's built-in check-and-repair tool. It inspects a disk's structure — the file system bookkeeping that tracks where every file lives — and fixes the problems it can. Clicking the button is easy; running it on the right things, in the right order, is what most people miss.

Run First Aid on a volume

1. Open Disk Utility from Applications → Utilities, or press Cmd+Space and type its name.
2. Choose View → Show All Devices. The sidebar now shows the full hierarchy: the physical disk at the top, the APFS container beneath it, and the volumes inside that.
3. Select a volume — Macintosh HD - Data, for example — and click First Aid in the toolbar.
4. Click Run and let it finish. The volume may be locked while it's checked, so apps can pause briefly. Don't force-quit Disk Utility mid-run.

This works the same on macOS 13 Ventura, 14 Sonoma, and 15 Sequoia.

Check in the right order: volumes, then container, then disk

Apple's recommendation is to work from the bottom of the hierarchy upward. Run First Aid on each volume first, then on the container that holds them, and finally on the physical disk at the top. Each level stores different structures: volumes hold file and folder records, the container manages how volumes share space, and the disk level holds the partition map. Fixing volume-level errors first means the container check isn't tripped up by problems below it.

You can run the same checks from Terminal if you prefer:

# Check a volume without changing anything (read-only)
diskutil verifyVolume "/Volumes/Macintosh HD"
# Repair it — this is the same operation First Aid runs
diskutil repairVolume "/Volumes/Macintosh HD"

There's no undo to worry about here: verifyVolume only reads, and repairVolume corrects broken file system records rather than changing any setting. It never deletes your files.

Repairing the startup disk needs Recovery mode

First Aid can check the disk you're booted from, but it can't fully repair a file system that's in active use. If it reports errors on your startup disk, restart into macOS Recovery and run it from there:

1. Apple silicon: shut down, then hold the power button until you see Loading startup options, and choose Options → Continue.
2. Intel: restart and hold Cmd+R until the Apple logo appears.
3. Choose Disk Utility from the Recovery window.
4. Run First Aid on Macintosh HD - Data, then Macintosh HD, then the container and the disk.

What the results actually mean

• "Operation successful" with a green check means no problems were found, or minor ones were found and repaired. Either way, you're done.
• "File system check exit code is 8" or "found corruption that needs to be repaired" means real damage. Run First Aid again — repairs sometimes take two passes.
• Repeated failures mean the file system can't be repaired in place. Back up immediately, then erase the volume in Disk Utility and restore from the backup.

One important limit: First Aid checks the file system's logic, not the drive's hardware. A disk that keeps corrupting itself may be physically failing even when First Aid reports success afterward.

If First Aid keeps finding errors

A disk that needs repair every few weeks is telling you something. Back up now, then check whether the hardware itself is degrading — our guide to checking your drive's SMART status shows how to read the early warning signs before a failing disk takes your files with it.