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

I am also having an issue where peripherals connected via USB are not being recognized after sleep. If i unplug them from the back of the Mac Pro, and then plug them back in they re-appear. Anyone else noticing this? Again, this only started after 10.11.2

Same Problem. Mac Pro 2013, D300 cards, Samsung TV.

Tried connecting the monitor through HDMI and Thunderbolt, same result.

The issue popped up with 10.11.2.

Dear Apple: An update should sort out the rest of the bugs, not create new ones for us. Thank you.

I keep fiddling with this.. really annoying me. I have found another work-around. If you un-check the "Prevent computer from sleeping automatically when display is off" item in the System Preferences > Energy Saver control panel, when the monitors shut off the Mac Pro goes to sleep. When it wakes from real sleep and not just monitor sleep, both of my displays come back on without issues.

I don't really like this because I remote access a lot, so this helps with the monitor issue but kills my ability to remote in.

Experiencing the same problem with Mac Pro 2013 D500 and a pair of external ASUS PB278's, but not the attached Apple Thunderbolt Display.  They finally got this solved at times during the 10.9.x and 10.10.x series and now in 10.11.2 it's back.

Getting the displays back on is getting to be a juggling act and getting them back on isn't even consistent.  Sometimes turning their power on/off, {un/re}-plugging the cables, and putting the displays to sleep/wakeup.  Nothing consistent. This recurrent problem really calls into question the competency of whatever folks they have working on this part of their software and whether they actually QA this stuff. I'm really getting fed up with this.

I have the exact same monitors and the exact same problem.  Under Yosemite I had nothing but issues with the displays, but El Capitan fixed everything and it was stable.  Now, after running the OS 10.11.2 update, they no longer work on display port.  I've had luck running one of them off HDMI at 30Hz (which ***** in comparison).  The other works on Display port only after shutting the displays off and turning them on several times.  I have the lower right screen as a hot corner to do this.  I can't get them to work at all with both of them on Display port and I usually have to just reboot the computer too many times… it works 1 out of 10 times.  What a disappointment.  Please fix, Apple!  It worked before, you broke it!

15" MBP 2011;   AMD Radeon HD 6770M; LG monitor connected with mini-display port to HDMI cable.

Same symptoms. Sometimes starting system preferences/displays and fiddling-- most recently doing a 180° rotation-- will at least get the second monitor going again without necessitating a reboot, but something clearly amiss and seems to be software related. Started happening, as with OP, with 10.11.2 upgrade.

Worked fine under previous OS X versions.

Having Similar issue.  Recently went from a 3 monitor set up to 2 with a new Samsung 28" UHD display using the HDMI port when my mac pro wakes from sleep it only wakes the monitor connected via the thunderbolt to dvi adapter.. the HDMI is not recognized even if I unplug it and re plug it in.   I have to restart the machine to get the UHD back up... Sometimes if I wake the monitor manually before waking the mac pro it works fine.. this was all fine before the 10.11.2 update.

Should add I've tried a bunch of troubleshooting, my mac-mini is connected to an Onkyo amp which runs everything, and outputs to a samsung LCD.

The issue doesn't just turn up if my mac sleeps, it's if I leave the HDMI connected amp/display off for any substantial period of time.  If I start up my computer with the amp turned the the MM input, it loads fine.. then i can switch inputs/turn amp on/off and have the MM screen show up no problem.  If I goto another input for a while, or turn amp off for a while and try to go back to the MM, then I can't recover the screen.

My MM has all sleep settings/screensavers etc. turned off.  There must be some internal timeout function which causes the issue when the connected display isn't on.

I'm having the same problem with my Mac Mini 2.5 GHz Intel Core i5... I have two monitors connected to the machine, both of which are HDMI cabled.  One of them is connected to the Display Port via a Belkin HDMI-Display Port converter.  This setup has worked for the last five years without a hiccup... and suddenly, after upgrading to El Capitan, the monitor connected to the Display Port is no longer there when the computer wakes from sleep.

Rebooting and resetting the PRAM do nothing at all for me.  The only reliable fix I've found is to completely unplug the Display Port adapter AND the HDMI Cable.  Then I plug just the Belkin adapter back in the Display Port on its own.  Finally, I connect the HDMI cable to the adapter, and for some bizarre reason, that combination works... but ONLY that combination.  If I try just plugging the adapter back in the Display Port without first disconnecting from the HDMI cable, no dice at all.

I'm sort of glad I figured out a workaround, but this is like flying in an airplane where you need to go outside every so often and glue the wing back on mid-flight.  I own four macs, including two Mac Pros, and I have been *plagued* with all kinds of wacky display issues every since the emergence of Mavericks.  This is terribly frustrating because one of the central reasons I own macs in the first place is their ability to seamlessly project on multiple different displays.

Same issues after updating as all the folks here are reporting. I'm on a Mac Pro (Late 2013) with multiple Thunderbolt monitors. The rig had been working great until the Mac OS X El Capitan 10.11.2 (15C50) update.

I'm disappointed with Apple support. They claimed to have never heard of this issue, even though it's been well documented here in the discussions. Went through the PRAM routine, re-installed El Capitan, etc. as Apple support suggested.

Then I contacted the monitor manufacturer, who said it was totally with the OS. Then got back with Apple, who still blamed the monitor company for bad advice, then suggested I downgrade to the 11.1 (Really?!?). No apology or acknowledgment from Apple other than dismissively calling this a "glitch" they've never heard of.

Same issue, Mac Pro 2013, Toshiba tv.

Flipping the cable around so the HDMI to ??? adapter is at the monitor end seems to make it work.  A straight hdmi cable did not work.  Didn't spend a lot of time trying to understand why a change in my hardware config was even necessary after this update.

I have the exact issue also - Mac Mini (Mid 2011) 2.7 GHZ i7 Processor w/ AMD Radeon 6630 Graphics.  Running HDMI into Yamaha AV Receiver, output to Samsung 50" LCD (This is my media center!!)  If I change inputs on my TV or sources on my receiver, the HDMI output to the receiver disappears.  Only a hard reboot brings it back.  I normally leave this Mac on as we toggle between Television / Internet sources.  I am relieved that it is not a Mac or Yamaha issue, but it is still a real pain.  I've tried everything.  Hope they are writing a software update to fix this!!

15" MBP 2011;   AMD Radeon HD 6770M;

Same symptoms. Sometimes starting system preferences/displays and fiddling-- most recently doing a 180° rotation-- will at least get the second monitor going again without necessitating a reboot, but something clearly amiss and seems to be software related. Started happening, as with OP, with 10.11.2 upgrade.

Energy PrefsPane in 10.11.2 El Capitan is different:

Am turning "Display Sleep" off to see if this will work as you suggest.

Flipping the monitor orientation (secondary) with SystemPrefs/Displays works. Then simply hit return to return the display to normal orientation (selects the default button "Revert" on the associated dialog box).

Same problem with a Mac Mini 2011 with El Capitan 10.11.2 connected via HDMI to Panasonic TC-L42E30 LCD Display, switched through Panasonic SU-HTB500 Soundbar. The soundbar manual says there is a 30 minute "inactivity" shutdown timer, after which time the display loses sync and cannot restore it. SImilarly to everyone else's complaints, the Mini's software driven display sleep is also incapable of waking. I have run the same setup for 5 years with NO issues, updated OSX last week, and now I have to power cycle the machine to wake the display.

Apple needs to fix this, multiple hard resets per day can't be good for my machine. It's certainly not good for my productivity.

Side note: wouldn't it be great if there was a keyboard shortcut that we could use to cycle display modes and resync video (*cough* fn + F4 in windows)? Constant poka yoke of removing useful features and critical failure analysis functionality is HUBRIS if OSX is not robust enough.