Re-installing components that are damaged or erased during the Mac OS X update process

For various reasons -- including user interruption as described in this article -- components of Mac OS X can be "stepped on" (erased or otherwise damaged) during the incremental update process (e.g. installing Mac OS X 10.4.9).

In order to remedy this issue, there are two options; one far simpler than the other:

Re-apply the current Mac OS X combination updater Try this first. It is perhaps the most consistently successful workaround for issues that materialize after an incremental Mac OS X update with good reason: re-installing the combo update can replace components that were damaged during the initial update process (the combo update is larger in size than the version-to-version [i.e. 10.4.8 -> 10.4.9] or "delta" update and makes any incremental release current [e.g. 10.4.1 -> 10.4.9])

Extract and replace The second, more tedious option is to extract the damaged component from the appropriate Mac OS X combo updater and replace the damaged file on your hard drive with the unblemished copy.

Your first step in this method is identifying the problematic component. This is usually an intuitive process, but can be narrowed down by the shareware application Pacifist, which will tell you which files were modified by the update in question, as follows:

1. Download and install Pacifist
2. Navigate to /Library/Receipts and find the receipt file for the version of Mac OS X you just installed, e.g. MacOSXUpdCombo10.4.9Intel.pkg. This is file contains a record of every item installed by the update. Drag it over the Pacifist icon.
3. You will be shown a list of all files modified by the update. The structure shown in Pacifist mimics the structure of your Mac OS X startup drive. For instance, if you click on the triangle next to "Applications," and you will be looking at the files the installer will place in your /Applications folder. Click on the triangle next to "System" then next to "Library," then next to "Extensions," and you will be looking at the files that the installer will place in your /System/Library/Extensions folder and so forth.

Look through the various folders until you find an item you think might be implicated in the issue you are having. Some are easy -- if you're having a hardware issue, look for problematic kernel extensions, which are located in /System/Library/Extensions/. An AirPort issue, for instance, might implicate the following files:

1. AppleAirport.kext
2. AppleAirPort2.kext
3. 108211.kext

Your best bet is to be comprehensive. Inspect the modified files thoroughly and identify any items that you think might be even remotely related. [For more clues on identifying problematic files, you may want to inspect your log files.]

After you are reasonably certain you have identified the culpable component, replace it via these steps:

1. Download the current Mac OS X combo updater appropriate to your system (from Apple's download page).
2. Drag the installer package (e.g. MacOSXUpd10.4.9Intel.pkg) onto the Pacifist application icon. [Note that that although it bears the same name, this is not the receipt file aforementioned. It is the file on the disk image you downloaded from Apple's Web site]
3. Find the file you are looking for by clicking the disclosure triangles to navigate.
4. Click the "Extract" button, and save the file to your Desktop or another location (you will have to enter your administrator password)
5. On your Mac OS X startup drive, navigate to the appropriate folder and locate a similarly named file (again, remember Pacifist's display of contents mimics the directory structure of your Mac OS X startup drive). Move it to another location for safe keeping.
6. Now drag the file from step 3 (the one that you retrieved from the Mac OS X install package) into the mirror location on your hard drive, in effect replacing the damaged file (installed by the updater) with and older copy -- you will have to enter an administrator password.
7. Restart your Mac

Alternatively, you can skip steps 4, 5 and 6 and simply click the "Install" button in Pacifist once you've found and selected the appropriate file in the package. However, skipping these steps won't let you ensure that the intended directory structure actually exists. If it doesn't, your installation is more severely damaged, and you should try re-installing the combo updater again or consider an Archive and Install.

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