the Joy of Macs Mac OS X Recipe Mac OS X
Carefully updating Mac OS X
17 Nov 12
[ Overview | Ingredients | Step by Step | Feedback]


Mac OS X Software Update makes it very easy to apply updates to Mac OS X and bundled applications. Unfortunately, Software Update actually makes it too easy because there may be problems lurking in the system that cause the update to fail, corrupt the system, or both.

The wise (often battle-scarred) user will take some extra effort to ensure a successful update.

Most of the step-by-step portion of this recipe was drawn from John Sawyer's response to an article originally on the MacFixIt site (now on CNET Reviews).


Step by Step

Essential steps

  1. Startup your Mac from a disk utility CD/DVD (see Ingredients).
  2. Run the disk utility to diagnose and repair corruption of the Mac OS X volume.
    1. Apple's Disk Utility will do a quick repair of serious problems. Disk Utility is found in the Utilities menu on the Mac OS X install disc.
    2. DiskWarrior and TechTool Pro are recommended because they do a more thorough repair.
  3. Startup from the volume containing Mac OS X.
  4. Run Disk Utility's Repair Disk Permissions function on the startup volume.
  5. Install the update.
  6. Shutdown, wait one minute, and power up your Mac. (Shutdown and power up is a cleaner, more complete Restart.)
  7. Run Repair Disk Permissions again before running any applications.

Extra install steps by John Sawyer

If you want to be even more thorough in your pre- and post- OS X installs/updates, you might want to add these steps to those that MacFixIt recommends:

(I know all these "extra" steps can be tedious, but we're working with a "big boy's" operating system now, and so we're "supposed" to have more work to do to maintain it—maybe Apple will get the point someday and make more of this automatic or unnecessary)

Before running the installer/updater:

  1. Run Apple Hardware Test to check for RAM problems.
  2. Use a utility to delete as many cache files as possible.
  3. Reset the Mac's NVRAM/PRAM: power down the Mac, then power it up, and before the screen lights up, hold down Command-Option-P-R. You need to do this from a powerup, not just a restart, since doing it from a powerup clears the NVRAM chip in addition to the PRAM chip.
  4. Reset more settings using Open Firmware: restart the Mac while holding down Command-Option-O-F. When the Open Firmware screen appears, enter:
        set-defaults [then press the Return key]
        reset-nvram [then press the Return key]
        reset-all [then press the Return key]
  5. Unplug all USB devices from the Mac's USB ports (including hubs, non-Apple keyboards, mice, etc.), except the original model (if available) keyboard and mouse.
  6. Unplug all Firewire devices from the Mac's Firewire ports.
  7. If you're going to be running an updater while booted from the target volume, start up the Mac in Safe Mode first, to disable any extensions that might interfere with the updater:
    1. Hold down the Shift key at startup, and keep it held down until you see the message "Safe Boot" appear.
    2. Then let go of the Shift key.
    3. Hold [the Shift key] down again as soon as the startup splash screens disappear and the screen turns blue, just prior to the desktop appearing—pressing the Shift key a second time prevents any startup items from starting up, which might also interfere with an updater.
  8. Log into an admin account, and don't have more than one user logged in, since having more than one user active can cause trouble for some updaters.
  9. Don't run ANYTHING while the updater is running—no other applications, System Preferences, etc.—if you open a file or application that the updater is trying to update, it may fail to update it properly, or cause even worse trouble.

Resolving post-install problems by John Sawyer

If you have problems after the install/update:

  1. Reset the Mac's NVRAM/PRAM and Open Firmware again.
  2. Run Apple Hardware Test again to check for RAM problems. Whether or not it finds any, if you're still having problems, shuffle the RAM boards into a different arrangement.
  3. Open the Mac and press the PMU or Cuda reset button on the logic board to clear out any scrambled settings.
  4. Reset the clock and calendar to the current date, or else a lot of files will be marked as modified in some absurd year after you pressed the Cuda reset button.


Please send questions & comments to Ward Clark.

Revision History

17 Nov 12 – Update MacFixIt link to its new home on CNET.
02 Mar 05 – Replace Restart with Shutdown and power up in Essential Steps.
19 Oct 04 – created