Fix For External Screen Not Coming Alive After Standby On A Mac

howto

Problem:

You have an external display for your MacBook Pro and suddenly the external screen does not
come back alive after a standby.

I have a late 2016 model MacBook Pro (with touchbar) and I have a BenQ Ultrawide usb-c display.
Mostly I have my MacBook Pro closed when the external display is connected.
Normally I just had to touch my keyboard or mouse and my screen would come back alive.
I have no idea why but suddenly it didn’t anymore.

Solution

Although I don’t know why it happened. I did want to find a solution because it is completely irritating to
have to open you laptop and re-find your screen every time after a standby.

It took me hours of searching and lots of trying but I think the following is at least a solution.

Reset the NVRAM

  • Disconnect all external devices but keep the power cable connected
  • Shutdown the computer completely (not standby)
  • Press the Power button and then immediately press command option p r together
  • Keep them all pressed for at least 20-25 seconds (you might see some flickering on your screen)
  • Let the keys go and let the MacBook reboot

You might have to reset some system preferences like speaker volume, screen resolution, timezone etc.
In my case that was not necessary.

Reset System Management Controller (SMC)

  • Disconnect all external devices but keep the power cable connected
  • Shutdown the computer completely (not standby)
  • Press at the same time shift option control on the left side of the keyboard and the power button
  • Let the keys
  • Boot the MacBook with the power button.

These two combined seems to have my external screen back to normal behavior.

Only time will tell if it stays that way.

Hope it will help some of you with this problem.

References