I have a MacBook Pro (Retina, 13-inch, Early 2015, macOS High Sierra 10.13.6) which fails to detect an external display after is has woken up from sleep. (Update: Now running macOS Mojave 10.14.5 on a 13-inch 2018 model, and this is still a very annoying issue).

Here's my situation: I have an external monitor hooked up to to the MacBook's display port, I walk away from my computer for a few minutes and it goes to sleep. I come back, and no matter what I try, the only way for the MacBook to detect the external display again is to restart the computer!

I'm using a Mini DisplayPort to DisplayPort cable. I use the MacBook at home as well as at work; I've tried different ports on my computer, different cables, and different monitors; the issue is with the MacBook itself.

It used to be that when this happens, I manually put the MacBook to sleep and wake it up again, and voila, it would detect the external display again. But now the only way to consistently fix the issue is to restart the MacBook.

I've also tried opening the display settings, holding down the alt key, and clicking "Detect Displays". This does nothing.

Any ideas on how to remedy this problem?

  • Exactly same symptoms (MBP 2017). Only reboot helps. Tried to replace all cables, and tried 2 different thunderbolt docking stations. SMC and PRAM resets did not help either. – Dmitry Oct 26 '18 at 17:48
  • forums.macrumors.com/threads/… – Dmitry Oct 26 '18 at 17:59
  • Well, it's nice that my monitor starts working again after a restart, as oppose to not working at all :p – cornflakes24 Oct 31 '18 at 14:13
  • 3
    You'd think a trillion dollar company would put up some money to iron this bug that's been around for so long. – Moshe Gottlieb Apr 10 at 4:51
  • Still an issue on the newer macs :'( – cornflakes24 May 18 at 14:30

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