I was helping a friend to do a clean install on his Macbook Pro with the bootable Mountain Lion USB disk (By holding down the option key at boot up and choosing the USB Installer) but I got stuck with the following screen.

Since Apple is descriptive about its error messages, could you guys let me know what could be the problem here is?

enter image description here

  • USB drive not prepared properly.
    – duci9y
    Commented Feb 14, 2013 at 16:45
  • Do you know the model number of the MacBook Pro?
    – dwightk
    Commented Nov 19, 2014 at 2:42

1 Answer 1


It indicates that the MacBook Pro was not able to load the OS kernel from the selected disk. The usual reason for this is that it's an OS version that doesn't support that model (Mountain Lion supports MBP's starting with the Mid/Late 2007 models (see the specs). Another possibility is that the USB disk is damaged, improperly set up, or something like that.

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