I have a retina MacBook Pro running Mountain Lion with a 23" external display attached through the Thunderbolt port (DVI/Display Port adapter). I have the monitor configured as an extension to my internal display (arranged just above as it actually is placed on my desk).

The arrangement works very well. However, sometimes (~30-40% of the time) the external display remains blank if the MacBook Pro screens have timed out or the MacBook Pro has gone to sleep and I then wake the MacBook Pro (by pressing a key). The MacBook Pro still thinks that the external display is connected as the screen remains in extended mode and apps are also there (though invisible, if that's where they were placed before the screen/MacBook Pro went to sleep). If I disconnect/reconnect the display port (Thunderbolt), it does go to internal only, but I cannot get the external display back unless I restart the Mac. Any ideas?

  • I had the same problem with Lion and it persists after Mountain Lion. Restarting the monitor doesn't help, only switching between the Thunderbolt port or a MBP restart brings the external screen back. I guess, that one thunderbolt port runs more stable than the other. That must be a MBPro or OS problem.
    – user28097
    Aug 27, 2012 at 8:02
  • I now have exactly the same problem. Switched my 23" monitor from VGA to DVI connection. Now using an Apple mDP->DVI adapter on my MBP. While I had no issue with the VGA adapter the DVI one keeps my external screen blank when waking up by touching a key on the MBP (only display is sleeping, not MBP). I have to switch sources on the monitor to wake it up. Quite annoying. Would this be linked to the fact the the adapter is a passive one? I don't need an active one as I have "simple" FullHD resolution on my external monitor. Hope we will be able to resolve this one...
    – LudoMC
    Oct 12, 2014 at 8:47
  • And no improvement with Yosemite, but could it be fixed by software only?
    – LudoMC
    Oct 18, 2014 at 12:08
  • And finally, I resolved the issue with a no-name MiniDP -> HDMI adapter which does the job correctly...
    – LudoMC
    Oct 28, 2014 at 6:48

3 Answers 3


To get the display back without rebooting, I've had success doing this:

  • Disconnect the display
  • Wait until the display goes to sleep (set the timeout to 1 minute first)
  • Reconnect the display

To avoid the issue altogether, I've gotten into the habit of disconnecting the display before I leave the Mac.


I've decided there's a strong correlation (though not a very high sigma) between a monitor being on Thunderbolt port #2, and having this problem occur.

Thunderbolt port 2 is the one closest to you when sitting in front of the keyboard (Route String 3).

This would seem to indicate a hardware issue, whether or not it can be fixed in firmware/software is unknown. Also unknown is whether this issue occurs on all port 2s, or whether there's a quality issue on these ports in general (maybe not all Retina MacBook Pros have this problem?).

It's certainly distressing, since I shelled out on a 3k piece of hardware I want to last 3 or 4 years and there's a strong likelihood I'm just going to have this problem forever.


Open System Preferences/Energy Saver. Set Computer Sleep to "Never" and select any time for the Display to sleep.

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