Today i started my macbook pro and after some seconds it stopped working (just turned). I was not able to start it again. After some apple support search I found a page that described how to reset the SMC. After that the notebook startet. Then I switched it of again and tried to start it again but it did not start.

Now every start requires to reset the SMC. Then the notebook boots up.

Any idea what can cause this behavior?

  • Did you apply a firmware upgrade recently? Commented Nov 22, 2011 at 22:31
  • Does this start-up problem only occur when the machine was powered off, or does it also occur in rebooting? Once you have successfully started your machine, does it continue to run with no problems? (No further unexpected shutdowns?) Commented Feb 25, 2017 at 12:42

3 Answers 3


I'd try to boot the Mac into Recovery Mode and then Reinstall MacOS and see if that helps with the issue. If not then the hard drive needs to be taken in for repairs. You can also try inserting a new hard drive with MacOS on it and see if it boots.


Could be the PMU (power management unit) or I think it is now called SMC. Try this:


But do it only once. You could do more bad than good if you do it more than once.

Did you check if there was any firmware upgrade for your MBP?


I had experienced this with a 2008 iMac. I was also getting kernel panics.

The issue for me turned out to be a dying hard drive. I had previously thought it was bad memory but it wasn't.

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