macOS · Troubleshooting
Repair disk errors with First Aid
Run Disk Utility's First Aid tool to check a disk or volume for directory and file system errors and attempt automatic repair.
How to open Disk Utility First Aid
- Open Disk Utility from Applications → Utilities
- Select the disk or volume in the sidebar
- Click First Aid in the toolbar
- Click Run and review the results when finished
What you should know
- Available in Disk Utility under Applications → Utilities
- Can be run on internal, external, and APFS container volumes
- Startup disk repairs often require running from Recovery Mode
- Reports errors even if it cannot fully repair them
Why it matters
First Aid is the primary built-in tool for diagnosing and fixing file system corruption that can cause crashes, slow performance, or files that won't open. Running it periodically, and especially after an unexpected shutdown or crash, helps catch small directory issues before they escalate into data loss. Because the startup disk generally can't be repaired while actively in use, First Aid's integration with Recovery Mode is essential for resolving deeper system volume issues.
Best practices
- Run First Aid on external drives periodically, especially after improper ejection
- Use Recovery Mode's Disk Utility to repair the startup disk
- Back up important data before attempting repairs on a drive showing errors
- Re-run First Aid if the first pass reports it fixed some but not all issues
Common problems and fixes
- First Aid can't repair the startup disk while booted normally
- Restart into Recovery Mode and run First Aid from there instead.
- First Aid reports errors it can't fix
- Back up the data immediately and consider reformatting or replacing the drive.
- Process seems to hang for a long time
- Large or heavily fragmented drives can take significantly longer; avoid interrupting the process.
Tips and tricks
- Check the SMART status shown in Disk Utility as a first indicator of drive health
- Run First Aid on an external drive right after any instance of improper ejection
Frequently asked questions
Does First Aid recover deleted files?
No, it repairs file system structure, not individual deleted files.
How often should I run First Aid?
Occasionally as preventive maintenance, or immediately after a crash, improper shutdown, or drive errors.
Can First Aid damage my data?
It's designed to be safe, but a backup beforehand is recommended for any drive already showing symptoms of failure.
Related settings
- Disk Utility: Partition & Format DrivesUse Disk Utility to create or resize partitions, format internal or external drives to a specific file system, and erase disks before reuse.
- macOS RecoverymacOS Recovery is a built-in set of utilities for reinstalling macOS, restoring from a Time Machine backup, repairing a damaged disk, and resetting a forgotten password — all accessible without needing a working copy of macOS already running.
More Troubleshooting guides for macOS
- Erase & Reset MacErase All Content and Settings lets you wipe your Mac back to factory defaults — useful for major troubleshooting, or before selling, trading in, or giving away your device.
- Safe ModeSafe Mode starts your Mac with only essential system software and drivers loaded, skipping login items, most fonts, and system caches. It's a diagnostic first step used to determine whether a startup problem is caused by third-party software or a deeper system issue.
- Analytics & ImprovementsAnalytics & Improvements controls whether your Mac automatically sends crash reports and usage analytics to Apple, and optionally to third-party app developers, to help them find and fix bugs. It's separate from location services and general privacy settings, focused specifically on diagnostic and usage data.
- Activity MonitorActivity Monitor is macOS's built-in tool for seeing exactly what's using your Mac's CPU, memory, energy, disk, and network resources in real time, broken down by individual app and process. It's the first place to look when the Mac feels slow, hot, or the fan is running loudly.
- Apple DiagnosticsUse Apple Diagnostics, launched at startup, to test your Mac's hardware components including memory, logic board, and battery for underlying issues.
- Console: View System LogsUse the Console app to view real-time and historical system logs, crash reports, and diagnostic messages generated by macOS and installed apps.