Q: External monitor no longer wakes from sleep (10.11.2 update)

I have installed the 10.11.3 update and I still have a problem I believe is the same as this: when the MBPr "wakes" (it doesn't go to sleep, but turns off the screens) usually my two external monitors don't show anything, or just flashes of noise. The MBPr screen doesn't show anything, but it's turned on (you can see the backlight). Usually for the first moments I can see the login screen on my main external display, but then the "bands of noise" and everything goes dark.

What I have done since started to have this problem (don't remember with what update) is to turn off the external monitors. This usually makes the MBPr screen show finally the login screen. Once it is showing there, I turn on my external monitors, the MBPr recognizes them, changes the displays alignments, and I can work.

A few times I have just had to kill the computer, but it has been fortunately not that many times.

Macbook Pro 15", OS X Version 10.11.3, BenQ FP202W Display

The OS update did nothing to solve the problem for me. Sometimes rotating the display in preferences helps, sometimes not. It usually just takes time, like half an hour, then switching the monitor off and on again brings it back.

Has Apple even acknowledged the problem yet? One of the main reasons for buying Macs is that they just work straight out of the box. But not in this case.

The update seems to have made the problem worse.

I've suddenly starting having the same problem but I'm still running Mavericks!  Working fine before a recent 'security' update; now I have to unplug and reattached the DisplayPort cable to wakeup the external monitor if the MacBook Pro goes to sleep.  WFT!

Whichever way I attempt to solve this glitch, it is temporary. If I keep my MacPro busy, the second display stays up. But if I stop working for a few minute the display turns off. Then I have to resort to rotating or replugging or rebooting. The instability I'd crazy-making.

Unfortunately after upgrading to 10.11.3, my Eizo Ev3237 4k monitor won't wake up after sleep, the system clearly knows the monitor, led light turn white, just no signal coming out. My rig is Macbook Pro 2015 with Radeon M370x.

I have 2 Screens connected to Macbook through mDP, the Dell U2415h works just fine, but no luck for the be loved 4k Monitor.

Anyone got a solution?

I'm seeing a similar issue, that was not present prior to upgrading my 2012 Mac mini to El Capitan 10.11.3.  Even with Apple's latest patch, the two external monitors for my  2012 Mac mini are exhibiting behavior that is different from Yosemite, which originally worked perfectly.  Both monitors are standard HD (1920x1080) Asus PB238Q models.   The primary monitor, connected to the Mac using HDMI, wakes up consistently.  While the secondary monitor, using DisplayPort, fails to wake up.  As a terrible workaround, I've found that opening System Preference > Displays then clicking [Gather Windows] and rotating the second display's image 90 degrees wakes it up, and then I just click "revert" to ignore the change.  It gets the second monitor to respond, but it's a pain to do that each time the system goes to sleep.  The problem is also somewhat inconsistent.  If I tap the space bar or arrow key on the keyboard immediately after the system goes to rest, it will usually wake up with both monitors active, but after the system has been asleep for 5 minutes or more, the second monitor no longer comes back online.  The problem did not exist in Yosemite and I'm considering going back.

I Just had this happen on a brand new macbook pro 2.8 - everything was working great, had 2 display port to dvi monitors going via tbolt dock and an hdmi monitor, really working nice! Then i rebooted and none of them show up, rebooted and tried all kinda stuff, finally got 1 of the dock monitors on but when i pkugged in the 2nd it kills the first. Not been able to get all 3 running again... Le sigh, im supposed to wow my client that bought the mac for me tomorrow...

I upgraded to 10.11.4 just now and my Asus monitor still won't wake after sleep.  I decided to reset the NVRAM and that actually worked for me.  If you're still having problems, I would try doing this.

I have a MacBook Air (early 2014) and I don't know if this issue started with 10.11.3 or 10.11.4 since I updated both at once from 10.11.2 -- but I can say I now have this problem -- the external monitor (which was working perfectly until I updated) is no longer recognized when I wake the MBA up after closing the lid.

After much trial and error, it seems I can get it working again by disconnecting the monitor cable from the adapter; note that disconnecting the adapter from the MBA or the cable from the monitor doesn't make any difference; neither does powering everything off and restarting.

I have experienced this problem for the first time after updating to 10.11.4.  I put my MacBook Air to sleep by closing the lid when I was away from the monitor, then when I came back the monitor was black until I rebooted.  Using the hot corner did not work for me.

Yes, I am having this problem. With 10.11.4

I'm running 10.11.4 and the problem remains. I have to unplug my monitor and re-plug if I want it to appear. Each time I use it.

Same as GinaBeana: unplug and replug the power cable. Resetting NVRAM did not help.

Here's what finally worked for me -- changing the settings on the Energy Saver preferences and the Screensaver preferences, below.

Now, when the monitor goes to screensaver, it comes back when I press any key

When I'm done for the day, I set it to "sleep" (from the Apple drop-down menu), and it also comes back when I press a key.

Good luck!