Margin note: Direct and indirect problem causes after system updates

From time to time, we discuss troubleshooting issues on MacFixIt that ostensibly can't be directly traced back to the update with which they are associated. For instance, we previously noted an issue with iDisk synchronization that, for many users, seemingly occurred because of applying Security Update 2006-008. As stated in our initial coverage, this seems highly unlikely because Security Update only appears to make one specific change to specific QuickTime and Java components in order to preclude a potential vulnerability.

In some of these cases (such as the aforementioned), the situation is one of coincidence: just because a system update was recently applied does not indicate definitive causation for an issue that crops up upon restart or shortly thereafter. It's easy and intuitive to assume that a recent system change caused the problem, but other factors like network outages, improper configuration and more can also be at play.

In other cases, however, the issue is caused by a system update, albeit indirectly and generally due to preexisting circumstances that might manifest at some point regardless of whether or not said system update is applied. The reason for this alternative (to coincidence) scenario is that when a significant system update (security update, incremental Mac OS X release) is applied to Mac OS X, it's not usually a simple case of minor file modification. There are several other processes that occur during application of Apple updates that have the potential to modify system files and cause problems. One of these, quite simply, is a required restart. Though it can't reasonably be said that a given update caused an issue simply because it required the user to restart, the resulting condition is nonetheless indirectly related to the update's installation routine.

A prebinding routine is also performed by some Apple updaters -- a process that is meant for maintenance, but can sometimes actually expose underlying problems.

Finally, don't take release notes as comprehensive; inspect the package yourself. First download the indispensable utility Pacifist and install it, then follow these steps (these instructions will work for Security Update 2006-008 and some other Apple releases, but the process can vary):

• Click on the desired installer package while holding the control key (or right-click) to bring up the contextual menu, then select "Show Package contents"
• Double-click on the "Contents" folder to open it
• Double-click the file "Archive.pax.gz" to expand it -- a file called "Archive.pax" should appear on your Desktop (by default) or other user-designated location
• Drag the file "Archive.pax" over the Pacifist application icon to open it. You will then be presented with a list of files that are installed or replaced by the package. The directory structure listed mimics the folders in which files will be placed on your target installation volume. Below is an example showing the contents of Security Update 2006-008

Once you know which files are modified, you can better decipher whether or not problems may be directly caused by specific updaters and execute troubleshooting routines from a better-informed perspective.

Feedback? Late-breakers@macfixit.com.

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