How to fix Mac startup disk permissions errors and run First Aid on your Mac

Summary

This guide helps you troubleshoot and resolve: How to fix Mac startup disk permissions errors and run First Aid on your Mac. Follow the steps below to fix the issue.

Common Causes

If your Mac is behaving unusually — apps crashing on launch, files refusing to open, or the system struggling to boot — the culprit may be errors on your startup disk. macOS includes a built-in repair tool called First Aid, located within Disk Utility, that can diagnose and fix many of these issues without requiring a full reinstall. This guide walks you through running First Aid on your startup disk and resolving common permission and filesystem errors along the way.

Quick Fix Steps

If you're short on time, follow these condensed steps. Detailed instructions follow below.

1. Restart your Mac and hold Command (⌘) + R during boot to enter macOS Recovery.
2. Select Disk Utility from the macOS Utilities window and click Continue.
3. Select your startup disk (usually named Macintosh HD) in the sidebar.
4. Click First Aid in the toolbar, then click Run.
5. Wait for the process to complete, then click Done.
6. Restart your Mac normally and test whether the issue is resolved.

Detailed Instructions

When to Run First Aid

First Aid is worth running when you notice any of the following symptoms:

• Apps crash immediately or fail to launch
• Files appear corrupted or won't open
• The startup disk is greyed out or behaves erratically
• macOS reports "disk read/write errors" or similar messages
• Your Mac is unusually slow when accessing files
• Permission denied errors when accessing folders you own

Running First Aid from macOS Recovery

Running First Aid from Recovery is the safest option because it can repair the disk your operating system is currently running on. Follow these steps carefully:

1. Click the Apple menu and select Shut Down. Wait for your Mac to fully power off.
2. Press the power button to turn your Mac back on, then immediately hold Command (⌘) + R until you see the Apple logo or a spinning globe.
3. If prompted, enter your firmware password or select a user with administrator privileges.
4. The macOS Utilities window will appear. Select Disk Utility and click Continue.
5. In the Disk Utility sidebar, select your startup volume. On Apple silicon Macs and recent macOS versions, you'll typically see two entries: the container (e.g. Macintosh HD) and the data volume beneath it. Select the top-level container.
6. Click First Aid in the toolbar (or choose Edit > Run First Aid from the menu bar).
7. A dialog box will appear explaining what First Aid does. Click Run to confirm.
8. Wait for the verification and repair process to complete. This can take anywhere from a few minutes to over an hour depending on the size and condition of your disk.
9. When finished, click Done, then close Disk Utility.
10. Click Restart Mac from the Apple menu or choose macOS > Restart from the menu bar.

Running First Aid from Within macOS

If your Mac boots normally and you simply want to perform routine maintenance, you can run First Aid without entering Recovery:

1. Open Finder and navigate to Applications > Utilities.
2. Double-click Disk Utility to launch it.
3. Select your startup disk in the sidebar.
4. Click First Aid in the toolbar.
5. Click Run and wait for the process to complete.

Understanding First Aid Results

When First Aid finishes, it will display one of three outcomes:

• The volume appears to be OK — No errors were found. Your issue may lie elsewhere.
• File system was repaired — First Aid found and fixed issues. Restart and test your Mac.
• Repair attempted but failed — The disk has serious errors that First Aid could not resolve. See the troubleshooting section below.

Checking and Repairing Permissions

Modern versions of macOS (Catalina 10.15 and later) no longer use the traditional "Repair Disk Permissions" feature, because Apple moved permissions protection into a system component called Signed System Volume (SSV). This means most permission errors are now handled automatically by macOS. However, if you're experiencing permission-related issues with user files, try these steps:

1. Select the affected file or folder in Finder.
2. Right-click (or Control-click) and choose Get Info.
3. In the Sharing & Permissions section at the bottom of the info window, check that your user account has the correct access level.
4. If the settings appear locked, click the padlock icon in the bottom-right corner and enter your administrator password.
5. Adjust permissions as needed, then close the info window.

Troubleshooting

First Aid Reports the Disk is Damaged Beyond Repair

If First Aid cannot repair your startup disk, try the following:

1. Run First Aid again — sometimes a second pass completes repairs the first pass couldn't.
2. Boot into macOS Recovery and run First Aid on the disk from there, where it has full access.
3. If the issue persists, consider erasing and reinstalling macOS from Recovery. This preserves your files but replaces the system software.
4. For older mechanical hard drives, the disk may be physically failing. Back up your data immediately and consider replacing the drive.

Mac Won't Boot into Recovery

If holding Command (⌘) + R doesn't launch Recovery:

• On Apple silicon Macs, hold the power button until "Loading startup options" appears, then select Options > Continue.
• Make sure you're holding the keys immediately after pressing the power button, not before.
• Try using Option (⌥) + Command (⌘) + R or Shift + Option (⌥) + R to boot into a different version of Recovery.
• If Recovery still won't load, your disk may have severe corruption. Try booting from an external macOS installer.

Permission Errors Persist After First Aid

If you're still seeing permission-related errors after running First Aid:

1. Restart your Mac — many permission issues resolve after a fresh boot.
2. Reset your Mac's NVRAM/PRAM by restarting and holding Option (⌥) + Command (⌘) + P + R for about 20 seconds.
3. Boot into macOS Recovery and run First Aid from there to perform a more thorough repair.
4. If the issue is limited to specific files or folders, use the Get Info method described above to manually correct permissions.
5. As a last resort, back up your data with Time Machine and then erase the startup disk and reinstall macOS.

Still Having Issues?