We've received a few reports of problems after installing Security Update 2004-01-26. We'll have a report on these issues tomorrow, but today we wanted to revisit our long-standing advice on installing OS X updates. Installing any system update onto a drive that has minor (or major) disk or directory corruption is likely to result in problems. Likewise, incorrect system-level file permissions can result in a number of issues, and such incorrect permissions are often related to system updates. We recommend the following steps for installing such updates:
1. Before installing the update, check your startup drive for damage, and repair it if necessary. The easiest way to do this is to boot from the OS X Install CD and run Disk Utility (from the Installer menu). Click the First Aid tab, select your hard drive in the drive/volume list, and click "Repair Disk." If you have a third-party disk utility such as Alsoft's DiskWarrior, you can also run that for good measure.
2. Before installing the update, boot from your startup drive and repair permissions on your boot volume. To do this, launch Disk Utility (located in /Applications/Utilities), click the First Aid tab, select your hard drive in the drive/volume list, and then click "Repair Disk Permissions." (It's important that you do this while booted from your hard drive, rather than from the OS X install CD or another volume, in order to perform the "correct" repairs.)
3. Install the update.
4. After installing the update and rebooting, again repair permissions via Disk Utility as described in Step 2. This will ensure that any system-level permissions that may have been corrupted or changed incorrectly -- installers are notorious for this -- are reset to the correct values.
By following the above procedures, you're not assured a problem-free update, but you'll certainly have a "healthier" installation, which may help you avoid many of the issues that befall haphazard updaters. Some users may call these steps "overkill," but the MacFixIt staff who follow them religiously have yet to experience any of the update problems reported by users.