So you booted to a folder with a question mark? Sometimes, it appears for only a few seconds, and then your Mac boots normally. Other times, it stays there, and your Mac won't start. This error happens when your Mac cannot find a startup disk. Luckily, there are a couple of things you can do to fix it (most likely, even without losing your data).

What causes the no startup disk Mac error? 

A "no startup disk" error on Mac (often a flashing question mark) is caused by a number of factors:

  • Corrupted system files
  • Failed or improper macOS update
  • Actual internal drive failure (it may be due to physical or liquid damage or as the disk ages)
  • Incorrect startup disk selection or NVRAM issues
  • Accidental startup disk deletion
  • Incompatible firmware (Boot ROM version)

Luckily, you can fix all of these. First off, though, if you try to boot your Mac from external drive, check the connections to rule out that it is not a faulty cable that is causing the glitch. 

If you're trying to boot to internal drive, disconnect nonessential external devices — they may cause the issue, too. Next, follow the steps below to deal with the no startup disk error. This way, you might fix out-of-warranty devices without going to Apple. 

Will fixing the startup disk error cause me to lose all my data?

Usually, it will not cause you to lose your data, but it depends entirely on the method used and the severity of the damage. Standard repair tools — resetting NVRAM, running First Aid, or reinstalling macOS — are designed to repair file systems and mark bad sectors as unusable without deleting personal files. However, in cases of severe corruption, physical disk failure, or interrupted repair, you might lose your data.

What to do if there is no startup disk on your Mac

If you see the question mark for a few seconds

When this happens, the first thing you should do is reset your Mac’s NVRAM (non-volatile random access memory). It is responsible for storing and accessing important system settings, including startup disk selection.

For an Intel-based Mac:

  1. Shut down your Mac.
  2. Press the power button and hold down Command-Options-P-R.
  3. When your Mac plays a startup sound, release the keys after it sounds a second time. If your Mac has a T2 security chip, release the keys after the Apple logo appears and disappears a second time.
  4. Once your Mac has booted, ensure the correct startup disk is selected (see below).
Reset NVRAM

A Mac with Apple silicon will reset NVRAM automatically. To find out if your Mac is with Apple silicon, check out this list from Apple.  

Tip:

To minimize the possibility of Mac booting to a flashing question mark, run regular maintenance to keep your computer top-level performance. No, you don’t have to take it apart and clean the components! Instead, it is about software maintenance, such as reindexing Spotlight or repairing disk permissions.

The easiest way to do that is with CleanMyMac and its Performance feature. It can perform all tasks listed above quickly and easily. What’s more, you’ll be able to speed up Mail, flush DNS cache, and thin out Time Machine Snapshots. 

A few benefits of using CleanMyMac: 

  • The Performance scan is fast: according to internal data, it takes only 26 seconds to scan your Mac and run recommended maintenance tasks.
  • You can test it and other 25+ tools for 7 days at no cost — get your free trial here.
  • CleanMyMac cleans and protects your Mac, too: based on internal reports, on average users find and remove 10 GB of junk files, 4 duplicates, 4 similar images, and 1 malware after the first scan.

If the question mark doesn’t go away

You’ll need to boot your Mac in recovery mode and try to repair the disk with Disk Utility. Recovery mode (aka macOS Recovery) is a built-in troubleshooting system that allows users to repair disk errors, reinstall the operating system, restore files from Time Machine backups, or erase the startup disk.

For an Intel-based Mac:

  1. Go to Apple menu > Restart.
  2. Immediately press and hold Command+R.
  3. Don’t release the keys until you hear Mac’s startup sound or until the Apple logo appears.

For a Mac with Apple silicon:

  1. When turning on your Mac, press and hold the Power button.
  2. Keep it pressed until you see startup options.
  3. Click the Gears icon (Options) and hit Continue.
  4. You may be asked to select a user and enter their administrator password. Follow the onscreen instructions and press Next after any action you take.

Now that you’ve entered the recovery mode, choose Disk Utility from macOS Utilities and click View. Then, choose Show all Devices. Next, click the down arrow next to Macintosh HD, select the volume, and choose First Aid in the toolbar. Click Run.

Run First Aid from recovery mode

After all the steps are completed, repeat for the next volume up. And if the disk repairs successfully, don’t forget to restart your Mac.

If Disk Utility can’t repair the disk, you will need to reinstall macOS. But we suggest backing up your Mac first so that you can later restore it if needed. To do it, with Disk Utility open, connect an external drive to your Mac and select your internal drive in the sidebar. Now, choose File > New Image > Image from [Your Drive] in the menu bar, set the "Save to" destination to your external drive, and set Image Format to "read/write." Click Save and proceed with reinstalling macOS:

    1. Quit Disk Utility to return to macOS Utilities.
    2. Select Reinstall macOS.
    3. Follow the onscreen instructions to reinstall macOS
    Reinstall macOS from recovery mode

    If Disk Utility doesn’t show your disk in the sidebar and macOS Utilities can’t reinstall macOS, you will have to book a repair with Apple or an Authorized Service Center.

    Which macOS version will install from macOS recovery?

    macOS Recovery installs the current version of the most recently installed macOS. However, if you reinstall macOS from Internet Recovery (possible on Intel-based Mac only), depending on the shortcut you use, it will install either the latest macOS version your Mac is compatible with (Option-Command-R) or the version of macOS your Mac shipped with (Shift-Option-Command-R). If the latter is no longer supported, the closest version still available on Apple's servers will be installed.

    How to choose the startup disk

    If you reset the NVRAM to fix a problem, you should check if the correct startup disk is selected:

    1. Click the Apple menu and choose System Settings.
    2. Choose General > Startup Disk.
    3. Select the disk to start up from.

    Tip: For one-time changes, you can choose the startup disk by pressing the Option key on startup. It will show all bootable volumes. But it is possible on an Intel-based Mac only.  

    What to do if you accidentally delete your startup disk

    If you somehow managed to delete your startup disk, you will need to reinstall macOS after restarting in recovery mode. If you deleted the Recovery partition, your Mac would use Internet Recovery to reinstall. You will need to be connected to the Internet. Then, follow the steps above for reinstalling macOS.

    How to boot your Mac into Internet Recovery?

    Instead of pressing Command + R, use either the Option-Command-R or Shift-Option-Command-R shortcut. Refer to the tip above for when to use each of these.

    Key takeaways

    If your Mac can’t see its startup disk, don’t panic! Follow the steps above, and you should be up and running again in no time.

    • Immediate fixes: reset NVRAM, run First Aid from macOS Recovery (use Disk Utility) 
    • If resetting NVRAM and running First Aid do not help, reinstall macOS from recovery mode
    • The final resort is to contact Apple Support for more tips

    Frequently asked questions

    My Mac won't boot into recovery mode at all — what do I do?

    First off, make sure that you use your Mac's keyboard (not a Bluetooth or wired device) and that it is clean. Also, if possible, try connecting to Ethernet instead of Wi-Fi for better stability. If you have an Intel-based Mac, boot into Internet Recovery instead. Otherwise, create a bootable installer for Mac (learn more in this article from Apple).

    How much does it cost to fix a missing startup disk at the Apple Store?

    For an out-of-warranty device, the cost may be between $200 and $1,400. If the drive is physically fine but the OS is corrupt, service charges of around $50 may apply. If data needs to be recovered from a failed drive, costs can range from $700 to $2,000. Still, it is free if the Mac is under warranty or AppleCare+. Yes, you can try replacing the drive by yourself (if you have an old Intel-based Mac), but we do not recommend DIY solutions unless you are absolutely sure what you're doing. 

    How do I fix the startup disk error caused by an incompatible Boot ROM version?

    Tips outlined above should help fix it. If none of them worked, try to revive or restore your Mac. Check out this guide from Apple to see how to do it.

    Can I recover data from a Mac with a missing startup disk before fixing the error?

    Sometimes, it is possible. You can try booting into target disk mode to do it. However, you will need another Mac to do it. Learn more here.

    Why does my Mac keep randomly shutting down all apps and rebooting before the startup disk went missing?

    It indicates a severe disk failure or critical software corruption. To fix it, begin with reinstalling your macOS. If it still does not help, you might need to erase your Mac, meaning that you will lose all of your data unless you have a backup. You can erase your Mac from System Settings > General > Transfer or Reset > Erase All Content and Settings.

    What is the difference between a startup disk that is missing and one that is corrupted?

    The main difference lies in whether your Mac can detect the disk. A missing startup disk means the computer cannot find the drive at all, while a corrupted startup disk means the drive is found, but the operating system's files on it are too damaged to load.

    How do I fix the startup disk problem if my Mac is using a firmware password?

    You will need to enter the password when prompted. You can then disable it by choosing Firmware Password Utility/Startup Security Utility from the Utilities menu and choosing "Turn Off Firmware Password." If you forgot it, you must bring the Mac and original receipt to an Apple Store or authorized service provider to prove that it is yours, and they will remove the password.