OS X El Capitan: The Missing Manual

Startup Problems

Not every problem you encounter is related to running applications. Sometimes trouble strikes before you even get that far. The following are examples.

Kernel Panic

When you see the cheerful, multilingual dialog box shown in Figure B-2 you’ve got yourself a kernel panic—a Unix nervous breakdown.

Figure B-2. A kernel panic is almost always related to some piece of add-on hardware. And look at the bright side: At least you get this handsome dialog box. That’s a lot better than the Mac OS X 10.0 and 10.1 effect: random text gibberish superimposing itself on your screen.

(In such situations, user panic might be the more applicable term, but that’s programmers for you.)

If you experience a kernel panic, it’s almost always the result of a hardware glitch—most often a bad memory (RAM) board, but possibly an accelerator card, graphics card, or USB hub that OS X doesn’t like. A poorly seated AirPort card can bring on a kernel panic, too, and so can a bad USB or FireWire cable.

If simply restarting the machine doesn’t help, detach every shred of gear that didn’t come from Apple. Restore these components to the Mac one at a time until you find out which one was causing OS X’s bad hair day. If you’re able to pinpoint the culprit, seek its manufacturer (or its website) on a quest for updated drivers, or at least try to find out for sure whether the add-on is compatible with OS X.

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