How to repair a disk on a Mac with Disk Utility First Aid (macOS 26)

You are viewing the macOS 26 version of this guide, recorded on macOS Tahoe 26 (MacBook Pro) on 9 November 2026. It is kept as it was and not updated. See the macOS 27 version.

howtosimply.com/guides/how-to-repair-a-disk-on-a-mac-with-disk-utility-first-aid/ · Checked 9 November 2026 · MacBook Pro · macOS Tahoe 26

In this guide

Back up if you can
Open Disk Utility
Show all devices
Start with the last volume
Work upwards
Read the result
Restart
Good to know
Sources

Quick answer

Open Disk Utility, choose View, Show All Devices, and select the last volume shown under the disk. Click First Aid and Run. Then do the same for each item above it: volumes first, then containers, then the disk itself. For the startup disk, do this from macOS Recovery.

6 of 7 steps with real screenshots · 1 official source below

Device: Mac
Shown on: macOS Tahoe 26 (MacBook Pro)
App: Disk Utility
Real screenshots: 6 of 7 steps
Checked: 9 November 2026
Sources: 1 official, linked below

Step by step

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Back up if you can
A disk that already has errors can fail completely. If the Mac still runs, make a backup before the repair: how to back up a Mac with Time Machine.
Done
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Open Disk Utility
It is in Applications, Utilities. To repair the startup disk, or if the Mac does not start, open it from macOS Recovery: on Apple silicon hold the power button until the startup options appear and click Options. On an Intel Mac hold Command + R while it starts.
Done
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Show all devices
Choose View, Show All Devices. The sidebar now shows each disk with its containers and volumes indented below it.
Done
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Start with the last volume
Select the last volume listed under the disk, click First Aid and then Run. Enter your administrator password if asked.
Done
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Work upwards
When it is finished, select the item above it and run First Aid again. Go on in this order: all volumes, then each container, then the disk itself at the top. If the First Aid button is dimmed for an item, skip it.
Done
Read the result
A green tick means the item is fine or was repaired. If Disk Utility reports errors it cannot repair, the disk has to be erased and restored from a backup, or replaced.
Done
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Restart
Quit Disk Utility and choose Restart from the Apple menu.
Done

About this guide

First Aid checks the structure of a disk and repairs errors in it. It is the right tool when a Mac starts slowly or not at all, when files will not open, or when an external drive behaves oddly. It does not delete your data, but Apple still advises a backup first.

Menu names are from recent versions of macOS, where the settings app is called System Settings.

Good to know

While First Aid checks the startup volume, the Mac may stop responding for a few minutes. That is expected.

If the disk does not appear in Disk Utility at all, shut the Mac down, unplug all devices that are not needed, check the cable and power of an external drive, and try again.

A drive with repeated errors is on its way out. Copy your data off it and stop relying on it.

Related: external drive not showing up on a Mac: 8 fixes to try and Mac starts up to a black screen: 5 fixes to try.

In short: Back up, Disk Utility, View, Show All Devices, First Aid on the last volume, then upwards through volumes, containers and the disk, restart.

Sources