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 '12 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 '14 at 8:47
  • And no improvement with Yosemite, but could it be fixed by software only? – LudoMC Oct 18 '14 at 12:08
  • And finally, I resolved the issue with a no-name MiniDP -> HDMI adapter which does the job correctly... – LudoMC Oct 28 '14 at 6:48

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.


Already have a fix that requires disconnecting the display. This is undesirable due to the reset of window positions.

I am however curious to confirm your observation. I know I've tried forcing a display sleep and that hasn't helped at all.

Continued observations with a correlation on the single problem port mentioned above. Also, this has not been fixed with the newly released Macbook Pro Retina EFI 1.0 firmware update.


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.


Having the same issue, will post back if I ever figure it out.

I'm using two external Mini-Display-Port to DVI adapters. I've had luck restoring visibility by swapping thunderbolt ports. Not only is this a pain, but it resets all window positions.

And RE: Joseph's suggestion. I do not believe either of us consider not sleeping the PC a valid solution here.

  • "Detect Displays" does not wake display using SwitchResX. Powering off/on display does not wake display (when it comes back on, it immediately returns to sleep detecting no signal).

  • Using gfxCardStatus to force switch from discrete, to integrated, and back to discrete does not wake display.

  • Removing and reinserting cable from thunderbolt port does not wake display; although, the remaining integrated and tertiary displays that do work flash blue while "removing" the display from the display set, they also do this upon reinserting cable.

  • This issue seems to be unrelated to system sleep, I have system sleep disabled when powered by AC.

I'm currently trying to include or exclude the following correlations:

Of the two thunderbolt ports, is there a specific problem port? I know I've had this problem on both displays, and only one at a time, is this related to a specific problem port that's a recurring issue?

This issue seems only to recur when the display is asleep for an extended period. I cannot seem to reproduce the issue by simply sleeping displays.

My deterministic mindset is steering me toward the observation that the technology controlling a "switch" between Thunderbolt and Legacy DisplayPort is not properly passing signal from the display adapter through to the display.

DDC is working but TMDS is not?

Someone who knows more about Apple's Thunderbolt implementation might suggest additional troubleshooting steps, though I'm leaning toward a hardware issue that may or may not be fixable through firmware upgrade.

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