An interesting Mac problem today, one I’ve never seen before in all my years of messing about with Apples.

The user had applied some system updates from the App Store, and rebooted the MacBook Air as usual. Immediately on boot there was a kernel panic, with white text on a black background showing up over the grey boot screen. This happened even when trying to boot into safe mode (holding down Shift) though Recovery mode worked OK.

A quick google for the main text of the error – Unable to find driver for this platform: \”ACPI\”. – showed this was something others had seen at various times over the years when an update failed. The most common recommendation was to boot to recovery mode and reinstall OS X, though some other users suggested reapplying the most recent Combo updater to the affected machine. 

Combo updaters have all the files needed to update a machine from any point release of OS X to the latest, eg. 10.8.3 to 10.8.5 directly; the delta updaters only upgrade from one release to the next. Applying the combo updater is often a cure for small errors which seem to happen in incremental updates, as they replace a lot of files with fresh copies, eliminating small errors that can creep in over time.

I booted the afflicted Mac into Thunderbolt Target Disk mode, and plugged it into my MacBook – the disk showed up as expected. I downloaded the 10.8.5 Combo updater from Apple, and tried to run it. My grand plan fell apart at this point as my MacBook was running Mavericks, and the Combo updater plain refused to run, even to be applied to an external drive. After a quick look for a Mac running Mountain Lion which had a Thunderbolt port (my Mountain Lion iMac doesn’t sadly) I repeated the process, which took about 10 minutes to apply the full updater, and rebooted the Mac. Thankfully at that point it booted up perfectly fine, and afterwards had more updates applied from the App Store without problem.

So, lessons learned? Firstly, I need to keep some Mountain Lion machines around for the foreseeable future. Secondly, some people swear by always downloading the Combo updates from Apple and running those instead of the Delta updates from Software Update/App Store; I’m not at that point yet but I do start to see the attraction, and it does illustrate the utility of the Combo update for solving bizarre glitches.