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Troubleshooting Mac OS X

Troubleshooting Mac OS X

The following information may help users experiencing issues with their Apple computer. If you require more assistance the please contact your local College or departmental support or .

Safe Boot Mode

Safe Boot mode can be a useful option when diagnosing a problem and starts the computer with limited functionality:

  • Third party drivers are prevented from loading
  • The hard disk's integrity is checked
  • All non-OS fonts are disabled
To enable Safe Boot mode start the Mac holding down Shift. To return to the normal boot environment restart without holding down any keys. For more information see: OS X Mavericks: Start up in safe mode.

Log Files

Log files can be a very useful tool when trying to diagnose a problem. OS X provides Console (installed into /Applications/Utilities/) which is an easy method of viewing and searching logs. Only Administrative users will be able to read all system logs.

Alternate User Account

If having problems with an application, try testing it from a newly created user account on the same Mac, to see whether the problem lies with the application or with the user. If the problem is evident with the new user, it is very likely that the application install is corrupt. If the new user does not show the problem, it is probably corrupt files in the original user's home directory.

Reinstall Combo Update

The Combo updates are cumulative patches containing all updates released from the initial release up to the last 'point release'. For example the Mavericks 10.9.3 Combo update contains all updates from 10.9.0 to 10.9.3. Installing the Combo update can fix odd problems caused by a point release. The Combo updaters can be found at Apple's support website. After installing the update, run Software Update to install any additional software (usually security patches) that were released after the Combo update.

Target Disk Mode

Target Disk Mode starts a Mac into an intentionally very limited state. When this Mac is connected to another Mac via a Firewire or Thunderbolt cable (dependent on the hardware of the two Macs) the first Mac's disk is mounted as an external disk on the second. This can be extremely useful if a Mac will not boot, but access to the disk is needed. For more information see: Transfer files between two computers using target disk mode.

Reset User Password using Recovery Partition

The Recovery Partition replaces the install DVD with Lion (10.7) onwards. It is possible to reset any users' password using a tool only available in the Recovery Partition. It is also possible to reset the user home directory permissions using the same tool.

  1. Boot the Mac holding Command + R
  2. Choose Terminal from the Utilities menu
  3. Type resetpassword then press Enter
  4. Select the disk that the user resides on. Normally there will be only one listed.
  5. Pick the user account and enter the new password twice.

Please note this will not work on a Mac with an encrypted hard disk.


Apple provides the sysdiagnose tool for collecting information about Mac hardware and software. To invoke it press Command-Opt-Control-Shift-Full Stop. After a few minutes a folder will appear in Finder named sysdignose_date.tar.gz.

Last modified: 23 May 2014