I tried installing XCode on my MacBook Pro, but for some reason, it suddenly crashed. After a reboot, I saw a message my computer had to restart because of some system failure. After this message, I get the following text on my screen...

enter image description here

Does anyone have any idea what this text means and what to do about it?

  • It looks like your installation messed up the boot up sector, restart in recovery mode using CMD+R.
    – Ruskes
    May 2, 2013 at 15:38

2 Answers 2


That is a kernel panic during the pre-launchd portion of the startup cycle. The Apple signifies that the kernel has been loaded and the system is loading kext to get read to start launchd and load actual programs and user items.

You'll need to troubleshoot this or just try reinstalling the OS (erase if needed) if you have a good and recent backup of the user data.

If you don't have a backup or want to troubleshoot this for learning purposes, I would start as follows:

  1. Review Apple's troubleshooting guide:
  2. Unplug all accessories (yes even keyboard, monitor, everything - and then only connect the things you need and only when you need them)
  3. Boot to safe mode to see if it's a non-essential kext or configuration that's causing the panic. (so - I would try a safe mode boot with only a USB keyboard connected- wait 5 minutes and then plug in the monitor if it's a desktop Mac)
  4. Make a backup if you can boot into safe mode.
  5. Boot into recovery mode (or target mode) and make backups of any files you need.
  6. Resintall the OS (this shouldn't erase any user data and hopefully it will fix the panic).
  7. Optionally you can pause and dig into the /private/var/log/panic.log contents to see if you want to remove any third party kernel extensions.

Of course, it could actually be a hardware error and the Xcode install is pure coincidence (you needed to be doing something right before it failed), but there are lots of things you can do before taking it in for service in most instances where a KP happens at boot.

  • It's a MacBook Pro and lucky me, I have an SSD with the OS and a second internal drive with all my data, so no data is lost (I hope :)). I'll try to figure something with your tips! Thanks!
    – Michiel
    May 6, 2013 at 10:07
  • So, I restored my OS without having it returned to an Apple Store. And thanks to my SSD/HD combo, I have kept all my data! Thanks for the tips!
    – Michiel
    May 7, 2013 at 12:25

From the loaded kernel extensions in the backtrace, we can see that com.apple.iokit.CHUDKernLib is the bundle identifier of the kernel extension that is causing the kernel panic.

That makes sense, as the CHUD tools are part of the older Xcode installs.

If you're comfortable with the command line, what I would do is start up in single-user mode by holding down Commmand-S right after you start up your machine.

At the prompt, type the following and press return:

mount -uw /

This will mount the filesystem in read-write mode so you can make changes.

Then type the following 4 commands, pressing return after each line.

Make an "ExtensionsDisabled" folder to move the CHUD-related kernel extensions to:

mkdir /System/Library/ExtensionsDisabled

Change the current directory to the kernel extensions folder:

cd /System/Library/Extensions

Move the 3 CHUD*.kext kernel extensions to the disabled folder:

mv CHUDKernLib.kext CHUDProf.kext CHUDUtils.kext /System/Library/ExtensionsDisabled



If you're not comfortable with the command line, you could start up in safe mode and delete (or disable by moving elsewhere) the following 3 files:

  • Thanks for the help with CHUD. I installed x code 3.2.3 on 10.8.5 and got caught up in a constant CHUD crash... So yeah, boot up after holding down the shift key, and remove the CHUD extensions, reboot and all is well! Thanks again!
    – user64981
    Dec 16, 2013 at 11:22

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