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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?

cornflakes24
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  • 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
  • https://forums.macrumors.com/threads/no-signal-on-external-displays-after-mojave-update-2018.2128056/ – 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
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    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 '19 at 04:51
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    Still an issue on the newer macs :'( – cornflakes24 May 18 '19 at 14:30
  • anyone know if this is still an issue in 10.14.x? – BlueC Jun 19 '19 at 15:06
  • I'm on 10.14.5, and yes, still having this issue. – cornflakes24 Jun 19 '19 at 16:38
  • Same question asked a month ago: https://apple.stackexchange.com/questions/360100/macbook-pro-wont-display-on-2nd-external-monitor-until-restart?rq=1. And another one from almost 7 years ago: https://apple.stackexchange.com/questions/60993/external-display-on-macbook-pro-retina-mountain-lion-remains-blank-after-scree?rq=1. – cornflakes24 Jul 03 '19 at 02:58
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    Since there's apparently no solution to this except rebooting or plugging cables around, I suggest that everyone that has this problem creates a bug report at Apple, otherwise they might not notice. I have submitted a bug report including a video of the 2 displays flickering today. – narrowtux Jan 22 '20 at 14:00
  • Over the years, I've had 3 or 4 different MacBooks with 4 different external monitors (some connected via Display Port, some via USB-C) and every single combination of Mac and screen had these "No Signal" issues when waking from sleep. – Janosh Jun 23 '20 at 07:37
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    February 2021 and having the same issue with my brand new macbook pro. We should definitely fill bug report. – The Doctor Feb 03 '21 at 21:54
  • issue persists for m1 macs – Gal Margalit Feb 22 '22 at 14:20
  • Using a 2020 MacBook pro. And now is May 2022. – r0n9 May 13 '22 at 03:45
  • I have fixed this problem 100% by turning off Automatic Graphics Switching in Energy settings and restarting. – trinth Aug 01 '22 at 17:25
  • same issue on a macbook pro m1 - on 12.5. An incredible pain in the... ahem – shicky Aug 09 '22 at 10:24
  • This is still a problem on my M1 Air running Sonoma. Interestingly, the second external display, powered by Instant View [colors a bit washed out & limited to 30Hz refresh], is rock-solid at waking after sleep. It's only the native signal that doesn't work reliably. – cjm Oct 16 '23 at 20:06

4 Answers4

8

I still have the same issue on a macbook pro 15' 2018.

Unplugging and plugging again the screens helps without having to restart the whole thing... except that all open windows jump to the main screen.

.

///// EDIT solved the issue through an external thunderbolt dock

I am using the Thunderbolt 3 Dock of Glyph now. My external screen is connected to its Display Port port. After waking up the screens behave normally. When I take a break, I power off the external screen and power it on before waking up the computer. In the tips I got from Glyph, they do ask you to turn off Energy Saving options when connected to the dock, but it all seem to work fine,

quasi
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5

I've found the system knows the other monitor is there, it just can't rouse it. Fastest work-around I've devised so far:

  1. Open System Preferences
  2. Go to 'Displays'
  3. Click 'Gather Windows'
  4. On the panel for the external display, choose one of the rotation options. (Seems that forces the system to give itself a kick and the external display will wake up, albeit upside down.)
  5. Helpfully, there's a 'Revert' button already focussed. Just press Enter on your keyboard and it'll spin back around.

Done.

Colin James Firth
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1

I experience similar problem and Google brought me here. Though as long as I don't unplug the cable it would always work fine. If I unplug it to take away the laptop and come back again one of my two monitors (the one converted from Thunderbolt to HDMI) won't work. However the other one with Thunderbolt to DisplayPort always works.

My solution is to connect it to a different port and most of time it would just work again.

Allan Sun
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  • I've experimented with this, and the following seems to work:
    • Connect the monitor using a display port
    • Set on the monitor the display port version to 1.1, not 1.2

    Hope it helps someone...

     – Karel Kubat Jun 01 '21 at 20:25
1

I FINALLY found a method that works every time -- it's half voodoo, half witch's brew.

my setup

I'm running a 2019 MB Pro, one monitor connected via dock and display port, one monitor connected via usb-c adapter and HDMI. In my case, the display port monitor was one that never would wake from sleep. After much fiddling around with trying different methods, I found a way to reliably start using both monitors again without restarting.

steps to get all external monitors working again without rebooting

  1. Power OFF the display port monitor
  2. Wake computer from sleep
  3. Wait until I see a stable display on the HDMI monitor
  4. Power ON the display port monitor -- flickering on all screens ensues as the computer attempts to wake the displayport monitor up
  5. Unplug the dock (the display port monitor) from the Macbook
  6. After a moment, plug the dock back in.

Don't know why this works. Until I figured this out, the only way I could get it working again was to restart the MB Pro.

Hope this helps!

johnL
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  • I am also facing this issue regularly. Even this workaround does not help. I also have bluetooth issues when the macbook pro is running for a longer time, my mouse gets disconnected and I have to restart bluetooth. Further I bought a premium monitor with USB C as docking station. It charges my macbook but plugging USB devices to that monotir make them unavailable after sleeps. Battery is also dead and fingreprint sensor does not work anymore, I am affected by keyboard bug repeating keystrokes, etc. So in the end I go away from apple as I am too frustrated. – Jörg Jan 25 '22 at 13:45
  • It's worked for me on MacBook Air (MBA): I removed the Thunderbolt cable/plug from MBA and put my MBA to Sleep. So, I woke up and powered on my external monitor (because turns off automatically after a time with no signal) and plugged in the Thunderbolt and got success! thanks – Jonas WebDev Jan 02 '23 at 23:06