If your Mac will not start normally, you can often repair its startup disk from macOS Recovery using Disk Utility. Start in Recovery, open Disk Utility, choose View > Show All Devices, and run First Aid on the volumes, containers, and physical disk in the correct order. If First Aid cannot repair the disk, back up or recover your data if possible before erasing the drive or seeking service.
Quick Answer
- Shut down your Mac.
- Start macOS Recovery:
– Apple silicon: Press and hold the power button until Loading startup options appears, then select Options and Continue.
– Intel: Turn on or restart the Mac and immediately hold Command-R until you see the Apple logo or a spinning globe. - Choose Disk Utility in the Recovery window and select Continue.
- Choose View > Show All Devices.
- Run First Aid on each volume, then its container, and finally the physical startup disk.
- Restart your Mac and test it.
First Aid checks and repairs file-system errors. It does not recover deleted files, repair physical hardware damage, or guarantee that a failing drive is safe to use.
Before Repairing the Startup Disk
A startup disk contains macOS, applications, settings, and personal files. Although First Aid is designed to repair file-system problems without deleting your files, disk repairs can involve risk—especially if the drive is failing or already has serious corruption.
Before proceeding:
- Disconnect nonessential external drives, USB accessories, and hubs.
- Keep the Mac connected to power.
- If the Mac starts normally, back up important files first.
- Do not interrupt First Aid while it is running.
- Be prepared to wait; large or damaged disks may take considerable time to check.
If the disk is encrypted with FileVault, Recovery may ask for the password of a user who is authorized to unlock it. Enter the password when prompted. Do not guess repeatedly if you are unsure; use the correct Mac login password for an authorized account.
If the internal disk does not appear in Disk Utility, see How to Fix a Startup Disk Not Showing on Mac.
Start macOS Recovery
The correct startup procedure depends on whether your Mac uses Apple silicon or an Intel processor. If you are unsure, try the Apple silicon method first. Holding the power button on an Intel Mac does not provide the same Recovery startup process, so use Command-R if that method does not work.
Start Recovery on an Apple silicon Mac
- Shut down the Mac completely. If it is frozen, hold the power button until it turns off.
- Press and hold the power button.
- Release the button when you see Loading startup options.
- Select Options.
- Click Continue.
- Select an administrator account if prompted, then enter its password.
The macOS Recovery window appears after startup completes.
Start Recovery on an Intel-based Mac
- Shut down the Mac.
- Turn it on, then immediately press and hold Command-R.
- Release the keys when you see the Apple logo, a spinning globe, or the macOS Recovery window.
- Select an administrator account if prompted and enter its password.
If Command-R does not work, shut down the Mac and try again. Press the keys immediately after pressing the power button. A wired keyboard may work more reliably than a wireless keyboard during startup.
If Recovery does not load
Check that the Mac is connected to power and that the keyboard is responding. If you see a spinning globe, Recovery may need an internet connection. Connect to a reliable Wi-Fi network when prompted.
If the Mac starts from another disk or displays a flashing question mark, the startup disk may be unavailable, the system may be damaged, or the Mac may be selecting the wrong startup disk. Do not erase anything yet if you need files from the internal drive.
Open Disk Utility and Show All Devices
- In the macOS Recovery window, select Disk Utility.
- Click Continue.
- In the menu bar, choose View > Show All Devices.
The default Disk Utility view may show only mounted volumes. Show All Devices reveals the complete storage structure, including:
- Volumes: Usable file-system areas that appear as disks in Finder.
- Containers: Storage structures used by APFS, the file system commonly used by modern Macs.
- Physical disks: The actual internal SSD, hard drive, or external storage device.
The names will vary. The startup volume may be called Macintosh HD, but it could have another name. On many Macs, you will also see a separate Macintosh HD – Data volume. Do not rename, erase, or delete items during this repair.
For more help identifying the storage hierarchy, see How to Use Show All Devices in Disk Utility on Mac.
Run First Aid in the Correct Order
Apple’s Disk Utility repair process works best when you begin with the lowest-level items and move upward through the storage structure. In practice, run First Aid on the volumes first, then the container, and finally the physical disk.
1. Repair the data volume
In the sidebar, select the indented data volume, often named Macintosh HD – Data. Click First Aid, then click Run.
Read the result when the check finishes. If Disk Utility reports that the volume appears to be OK or was repaired, continue to the next item.
2. Repair the system volume
Select the system volume, often named Macintosh HD, and run First Aid again.
On newer macOS installations, the system volume may be protected and mounted in a way that limits changes. Disk Utility can still check it and may report that no repairs are necessary.
3. Repair the APFS container
Select the APFS container above the volumes. It may have a name such as Container disk3, although the number can differ. Click First Aid, then Run.
The container manages space shared by APFS volumes. Repairing it can address problems that are not visible when checking an individual volume.
4. Repair the physical startup disk
Select the top-level internal physical disk. It may show a manufacturer name, a model number, or a label such as APPLE SSD. Run First Aid one more time.
This is the device that contains the container and volumes. Make sure you select the internal startup disk rather than an attached backup drive or installer.
If you need a reminder about the individual First Aid workflow, see How to Repair a Mac Disk with First Aid.
5. Restart the Mac
When First Aid finishes:
- Quit Disk Utility by choosing Disk Utility > Quit Disk Utility.
- In the Recovery window, choose Apple menu > Restart.
- Allow the Mac to start normally.
If the Mac opens to the login screen, test it for a few minutes. A successful startup does not necessarily mean a failing physical drive is healthy, so back up important files as soon as possible.
What to Do When First Aid Reports an Error
First Aid can report several different outcomes. The wording matters.
“The volume appears to be OK”
Disk Utility did not find a problem it could repair. If the Mac still will not start, the issue may involve macOS startup files, an incompatible system update, another connected device, or hardware other than the file system.
“The volume was repaired”
Restart the Mac and test it. If the same error returns, repeat First Aid once from Recovery. Repeated failures suggest a deeper problem, such as a failing drive or severe corruption.
“First Aid found corruption that needs to be repaired”
Run First Aid on the parent container and physical disk after checking the volume. Then run First Aid on the affected volume again. If Disk Utility still cannot repair it, do not repeatedly force repairs while ignoring your data. Focus on backing up or recovering files.
“First Aid process has failed”
Note the full error message. It may identify the affected volume or indicate that the structure could not be repaired. If the disk is accessible from Recovery, you may be able to copy files to an external drive before taking more destructive action.
Do not choose Erase merely because First Aid failed. Erasing removes the selected volume or disk’s data. Continue only after you have a current backup or have decided that the files are no longer needed.
If the Mac Still Will Not Start
After First Aid completes successfully, restart and test the Mac. If it remains stuck, try these non-destructive checks:
- Shut down the Mac.
- Disconnect all nonessential external devices.
- Start macOS Recovery again.
- Open Disk Utility and confirm that the internal disk and its volumes are visible.
- Run First Aid again if the original result indicated an error.
- Restart once more.
If the internal disk is visible and appears healthy but macOS still will not boot, the operating system itself may be damaged. From Recovery, you may be able to reinstall macOS without intentionally erasing the startup disk. The exact screens and available options depend on the Mac and its installed system.
Before reinstalling, confirm that important files are backed up. A reinstall is different from erasing the disk, but you should still avoid making system changes without a recovery plan.
When You May Need to Erase the Startup Disk
Erasing is a last resort because it deletes data from the selected disk or volume. Do not erase the startup disk unless you have a backup or no longer need the data.
You might consider erasing and reinstalling macOS when:
- First Aid repeatedly fails.
- The disk is readable but its file system cannot be repaired.
- You are preparing the Mac for a new owner.
- You have already recovered the files and want to rebuild the installation.
In Disk Utility, selecting the wrong item can erase more storage than intended. Confirm the name and hierarchy carefully. On an APFS Mac, erasing a volume is not the same as erasing the entire physical disk, but either action can cause data loss.
If the disk cannot be erased, disappears during repair, makes unusual noises, or repeatedly reports input/output errors, it may be failing physically. Software repair cannot fix damaged storage hardware. Stop using the Mac as much as possible and contact Apple, an authorized service provider, or a qualified data-recovery specialist.
Troubleshooting
Disk Utility cannot unlock the startup disk
Select the locked volume in the sidebar and look for an Unlock option. Enter the password for an authorized FileVault user. If you do not know the password or recovery key, Disk Utility may not be able to access the encrypted data.
First Aid is grayed out
Make sure you selected a disk or volume in the sidebar. If the selected item is read-only, not mounted, or protected by Recovery, some actions may be unavailable. Try selecting the parent item or use View > Show All Devices first.
The internal drive is not listed
Shut down the Mac, disconnect external devices, and start Recovery again. If the internal drive remains absent, the problem may involve the storage hardware, its connection, or the Mac’s logic board. Do not erase an external disk as a substitute for repairing the missing internal drive.
First Aid keeps finding the same errors
Back up or recover your files immediately if the volume is accessible. Repeated file-system errors can indicate a failing drive. Avoid repeatedly restarting the Mac or writing new data to it until your important files are safe.
The Mac starts but is extremely slow
A damaged or failing startup disk can cause long pauses, application crashes, and slow logins. Back up your data and run First Aid from Recovery. If the problems continue even after a successful repair, have the Mac’s storage hardware evaluated.
Frequently Asked Questions
Does First Aid delete files?
First Aid is intended to check and repair file-system structures, not delete personal files. However, no disk repair is risk-free when a drive is badly damaged. Back up important data before running repairs whenever possible.
Can I repair the startup disk while macOS is running?
You can run some checks while macOS is active, but Recovery is preferable for the startup disk because macOS is not actively using it in the same way. Recovery also gives Disk Utility access to additional repair options.
How long does First Aid take?
The time depends on the disk’s size, condition, and the type of problem. Do not interrupt the process just because the progress indicator appears unchanged.
What if First Aid says the disk cannot be repaired?
Save or recover your files if possible. You can then consider erasing the disk and reinstalling macOS, or seek professional assistance if the data is important or the drive appears to be failing.
Will repairing the startup disk remove macOS?
No. Running First Aid does not intentionally reinstall or remove macOS. Erasing the disk is a separate action and can remove macOS, applications, settings, and personal files.
Final Thoughts
macOS Recovery and Disk Utility can resolve many startup-disk file-system problems without erasing your Mac. Use Show All Devices, run First Aid from the volumes upward to the physical disk, and treat repeated errors or missing hardware as signs to protect your data before taking further action.