Following the announcement of Apple's Thunderbolt Ethernet and FireWire adapters to accompany its latest MacBook Pro and MacBook Air offerings, Apple issued a small software update for existing computers that will allow them to properly use Apple's new adapters. Apple made this update available via Software Update so many would automatically install it on their systems, but unfortunately for many people this update has resulted in kernel panics and the inability to boot their systems.
In some cases, at startup the system will appear to boot normally but then issue a gray screen with the instructions to hold the power button to reboot the system, indicating a kernel panic. At other times, the system will simply display an "international no" symbol and not proceed with the boot process. For those experiencing kernel panics, the following text may be seen across the screen indicating a fault in the driver:
panic(cpu 0 caller 0xffffff800064ba7b): "Unable to find driver for this platform: \"ACPI'.\n"@/SourceCache/xnu/xnu-1699.26.8/iokit/Kernel/IOPlatformExpert.cpp:15 04
The Thunderbolt update applies a single plug-in update to the "IONetworkingFamily.kext" kernel extension, but it appears this plug-in contains a bug or two that is not compatible with at least some systems running OS X Lion 10.7.4. Unfortunately, being an update to an extension and not a new extension means that removing the extension or the plug-in is not an option and the only way to address this problem is to revert back to an older version.
If this happens to your system after installing the Thunderbolt update, then you can try the following options, which should clear up the issue and restore your system without losing any user data or settings:
- Reapply combo updater
First check to see if your system will start up in Safe Mode by holding the Shift key down at startup. If this is successful, then you can download the OS X 10.7.4 Combo updater and apply it to your system, which should replace the faulty kernel extension with the older one.
If you cannot boot to Safe Mode, then you can still apply the combo updater but you will need access to a second Mac running Lion in order to do so. To use the second Mac to reapply the combo updater, boot up your problematic Mac while holding the T key down, and you should see it load into Target Disk mode. Then attach the Mac to the second one either using a Thunderbolt cable or using a FireWire cable. When you do this the Mac's hard drive should mount as an external disk on the second Mac.
Next download the OS X 10.7.4 Combo updater and run it, but choose the hard drive of your faulty Mac as the installation destination instead of the internal drive of the working Mac. When the update is done, eject the Target Disk mode hard drive from your second Mac and restart the faulty system, and your computer should boot normally.
- Restore from backup
If you do not have access to a second Mac then your next best bet is to restore your system from a Time Machine backup if you have one. To do this, restart your system with the Command-R keys held down to load the recovery partition, and when the OS X Tools window appears choose the option to restore from backup. Then attach your Time Machine drive to the system and select the most recent backup to restore, which you should have created immediately before applying any of the recent software updates Apple has issued. If you do not have a recent backup, then avoid restoring from backup as this will result in you losing any new documents you created since the last backup you made.
Allow the restoration process to finish (it may take a couple of hours to do), and then restart the system. When finished, open Disk Utility and be sure to run a permissions fix routine on the boot drive, after which your system should be restored and functional.
- Reinstall OS X
A final approach, especially if you forgot to make a backup of your system before applying the recent updates, is to use the recovery partition to reinstall OS X. Similar to applying the Combo update, this will rewrite the OS and a working version of the faulty kernel extension to the hard drive, but will do so without requiring access to a second Mac. To do this, reboot your system and hold Command-R to load the recovery partition. Then open the OS X installer and proceed with the re-installation of OS X (you may need to provide your Apple ID and password to download Lion).
As with applying the combo updater, this process will not touch your user accounts and data, but will replace the OS with a fresh copy. After the installation is complete, restart the system and then immediately download and apply the combo update, which can be done through Software Update or by manually using the combo updater package. If you use Software Update, then be sure to avoid applying the Thunderbolt Update again as it will appear as an available update.