I have the same problem as this user, Air + Lion : plug in USB, keyboard/pad stop working , where the built-in keyboard and trackpad on my MacBook Pro stop working (and drop out of the USB devices listed) periodically when I plug in a USB hard drive.

The solution provided was to boot into safe-mode and clear the kernel extension caches, however I use FileVault 2 full-disk encryption which seems to disable booting into safe-mode.

Is there any way to clear the kernel extension caches in OS X 10.9 Mavericks without disabling FileVault 2 to get to safe-mode? I really don't want to de-encrypt and later re-encrypt the entire 750GB drive.

Alternatively, can kextcache be safely run on a system that isn't booted into safe-mode?

2 Answers 2


Holding down cmdS at boot time, for a boot drive that's FileVault 2 encrypted, presents the password dialog, then continues into Safe Mode.


If you can plug a FireWire or USB external drive (lest's name it ext_disk), I would suggest the following used receipe:

  1. Make a clone of your FileVault disk (let's name it FV2) on ext_disk with Carbon Copy Cloner
  2. Boot from ext_disk
  3. Open Disk Utility and unlock FV2
  4. Open Terminal or an xterm window to enter the following commands:

    cd /Volumes/FV2/System/Library
    /usr/bin/sudo touch Extensions
    tail -f /var/log/system.log
  5. Wait to see that kextcache is correctly upgraded on… FV2 (you don't risk anything since FV2 isn't bearing the cache in use by your running kernel) and terminate your tail with a +C, close your terminal window

  6. Reboot from FV2
  7. Check if all your misbehaving extensions are working correctly
  8. Safely erase ext_disk

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