Mac OS X - Troubleshooting Startup Problems

This document explains how to perform a Safe Boot in Mac OS X 10.2 or later and how to boot into the recovery partition for OS X Lion. This can help to troubleshoot startup problems when an OS installation disc is not available.

Safe Boot - OS X 10.2 and Higher

A Safe Boot will perform the following tasks:

A Safe Boot can potentially repair problems that prevent Mac OS X from starting properly.


To initiate a Safe Boot:
  1. Restart (or turn on) your Mac
  2. Immediately after the startup chime, press and hold the Shift key
  3. Once the gray Apple and progress indicator appear, release the Shift key
    • Note: Startup will likely take substantially longer than normal
  4. In Mac OS 10.4 or later, you will have to login to your account, even if it normally does so automatically.

While a Safe Boot can be helpful for troubleshooting, many services will be unavailable - specifically audio and network devices. To return to a normal boot, simply restart the computer without holding any keys. Generally, since the directory check occurs during the gray startup screen, you can reboot immediately after logging in.

Recovery Partition - OS X 10.7 and Higher

Self Help
NOTE: These procedures are not supported by the Help Desk. These instructions are provided for self help purposes only. Please contact the manufacturer or system developer for help.

Potential for data loss CAUTION: Please make sure your important data is backed-up on an external storage device (such as a CD, DVD, or external hard drive) before attempting this procedure. DoIT assumes no liability for data loss that occurs as a result of this procedure.

The Recovery Partition provides the following options:


There are two ways to access the Recovery HD:
  1. Upon startup, press and hold the command key and the R key until you see the Apple logo.
  2. Upon startup, press and hold the option key until you see the Apple logo. Then select the Recovery HD drive.

Once you have done this you will be taken to the Mac OS X Utilities screen shown below. Select a tool and click Continue to perform the desired function.