Troubleshooting with Single User Mode


If your Mac is having any of the following issues, try running Safe Boot first and if that does not work, try Single User Mode as detailed below.

  • Flashing question mark appears when trying to boot
  • Gray screen with a stuck or always showing progress bar
  • White or Blue Screen upon boot
  • Unable to repairing permissions
  • System is running extremely slow
  • Unable to log in


Corrupted Hard Drive, lost settings or files amongst may other issues.


Warning: Singer User Mode runs as the “root” user and you should be careful not to run any other commands other than those stated.

  1. Turn you Mac off if it is on. You can also hold the power button down until it shuts down if needed.
  2. Press the power button and the immediately press the Command (cmd) and the S key together and hold til you see a black screen with white writing.
  3. If the Mac got into Single User mode successfully then you will see the following at the bottom of the screen:
    “If you wish to boot the system: Exit”
  4. Type this command in exactly as you see it here (with a space between the k and –), then press Enter:

    fsck -fy

    If it comes back “command not found” then try again and check the spelling and spacing.

  5. Once you have done this, you will have white text scroll down the screen.
    • If the machine is fine or cannot find the issue it will say at the end:
      “The Volume Macintosh HD appears to be OK.”
    • If it does find some issues, you will get either of these messages:
      “Macintosh HD has been repaired.” or ”Macintosh HD has been modified.”

      It may give additional details with what have caused the issue if the drive cannot be repaired.
  6. If you get the any errors then you can try running Step 4 again a few more times.

If these steps do not work then it may need to have the operating system re-installed or a repair carried out by Apple.

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