Isolating issues in Mac OS X

By using the approach here, you can learn how to isolate an issue to its root cause, or at minimum to determine the sequence of events that causes the issue to occur. Using this approach may help you solve the issue, locate other support articles, write better posts to Apple Discussions, or communicate with AppleCare Technical Support.

Start by asking yourself basic questions about the issue that will help you describe it:

What is the issue?

When answering this question, be sure to note any alert or "error" messages that appear. Be sure to describe any unexpected hardware or software behavior, and any other details that seem relevant.

Users accustomed to reading logs should review them in Apple System Profiler for any relevant information. If you are not experienced with reading logs, it is generally best to ignore them unless instructed to search for a specific message.

When does it occur?

  • If you can identify a sequence of events that lead up to the issue, be sure to document each.
  • If the issue seems to occur at certain time intervals, be sure to record the times at which it happens. Does it happen only at certain times (for example, daily at 9:00) or on a periodic basis (for example, every 47 minutes)?
  • If the issue occurs so irregularly that you cannot yet describe when it happens, the suggestions below will help you troubleshoot the issue over time by making certain changes, then watching to see if the issue stops.
  • If the issue occurs at startup immediately following a third-party software installation, find out what you can do.
  • You can also troubleshoot any other issues that occur during startup.

If these suggestions do not resolve your issue, contact AppleCare or your nearest Apple Authorized Service Provider for assistance.

When did the issue start?

Note any recent changes to the computer and its software, since they could affect the issue. Was any new software or hardware installed?

Check documentation

After you can describe the issue, check known documentation sources, searching on key terms you have identified.

If an application program is affected, first check any "read me" files included with it. These may describe known issues.

If the issue is with a third-party product, check the manufacturer's or publisher's website for information about the issue.

Up-to-date software and firmware?

As a general rule, make sure you are using the latest versions of Apple and third-party software for best compatibility. Also make sure your computer's firmware is up-to-date.

Is it a software or hardware issue?

Pay attention to important clues.

  • If the issue seems specific to a certain application or Mac OS X feature, troubleshoot software before hardware.
  • If the issue occurs as the computer starts up--unless the computer does not turn on at all-- troubleshoot software before hardware.
  • For other issues, or when software troubleshooting does not produce a resolution, use the rest of this document.

Use Disk Utility to check for disk errors and permission issues

Such issues can contribute to other symptoms, but are usually easy to resolve.

Can you isolate to a hardware device?

Issues with a hardware device can sometimes appear to be software issues, but are not resolved with software troubleshooting. Eliminate hardware as a cause (or conversely, isolate the issue to software):

  1. Disconnect external devices. If the computer is an iBook or PowerBook computer, disconnect all external devices. For an iMac, disconnect all devices other than the Apple keyboard and mouse. For a Power Mac, disconnect all external devices other than one display (which should be connected to an original, built-in video port), and the original Apple keyboard and mouse. If this resolves the issue, add devices back one at a time (shut down first if the device requires it) to further isolate the issue.
  2. Insert the Apple Hardware Test CD that came with your computer (if one did). Use the extended test. If any issues are found proceed to step 3, or contact AppleCare or your nearest Apple Authorized Service Provider to arrange for diagnostics and service as necessary.
  3. Shut down the computer and remove any third-party memory upgrades, expansion cards, additional hard drives, or other internal hardware upgrades. If you are not comfortable doing this, an Apple Authorized Service provider can assist. A service fee may be charged if the issue is not related to your Apple hardware. Alternatively, you may wish to skip this step and go to "Reinstall Mac OS X" below.
    • If the issue is resolved, add your devices back one at a time. When the issue returns, remove the most recently-added device. If the issue goes away again, you have identified the cause. If software was included with the device, try deleting and reinstalling it. You may also wish to contact the vendor or manufacturer of that device for specific troubleshooting steps.
    • You may want to test devices on all available ports into which they can be used. If a USB device works on USB port 1 but not on USB port 2, try connecting other devices to port 2. It is possible that your computer's ports aren't working properly.

Reinstall Mac OS X

If an issue persists, reinstalling Mac OS X should resolve it.

  • For Mac OS X v10.6, simply reinstall Mac OS X v10.6 from its installation disc.
  • For Mac OS X v10.2, 10.3, 10.4, or 10.5, perform an Archive and Install installation.

    Tip: You won't be able to return to your previous System following an Archive and Install installation, but you can select the "Preserve existing Users & Network Settings" option to retain your original applications and settings, documents, and user accounts.

  • For Mac OS X v10.1.5 or earlier, reinstallation of Mac OS X requires erasing the Mac OS X volume. This is described in the next paragraph.

If the issue persists, back up any necessary data, start up from a Mac OS X Install or Restore CD, erase the Mac OS X volume, reinstall Mac OS X and restore any additional Apple software.

Reinstall additional software one item at a time, restarting the computer after each install. For best results, use the computer for several hours after each installation to determine if that particular software contributed to the issue. Reinstalling everything at once without noting when the issue returned may lead to a need to repeat this process.

Warning: Choosing Erase and Install will completely erase the contents of the chosen volume before installing Mac OS X. Be sure to back up your files before continuing.

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