10.12.4 display sleep bug

I have just installed 10.12.5 beta (16F71b) and so far it seems to have fixed the problem ... will report back if the home set-up is not fixed by the beta or if the problem recurs. (2x identical setups (5k i7 iMac + Dell P2715Q))

I updated to 10.12.5 Beta (16F71b) as well, but the issue remains for me. The iMac display and external monitors appear to try to wake up on key press, but all immediately turn off after. Continuing to press keys and so forth sounds like the OS is still functioning. I really hope this is addressed on 10.12.5 as this absolutely annoying.

Sorry to say even with the beta update to 10.12.5 (16F71b) the problem is still present but intermittently on at least one of my two set-ups (they should be identical!?).

Really annoyed! If it is not fixed in 10.12.5 then I am considering returning my computers.

10.12.5 (16F71b) is beta 5, so that's the most current version not fixing the problem. Disappointing.

10.12.4 introduced Night Shift, the mechanism for increasing the warmth of the screen in late hours. Given that this is a display subsystem change, it's possible the new display bug is related. Is there any chance that we all have that enabled? I've disabled it on mine and will see if the black screen problem returns. It's in the display system preferences in its own tab.

Adding another data point: I just got my own iMac 2014 Retina back from repair for an unrelated overheating issue. I believe the logic board was swapped out because the MAC address has changed. This problem persists with that brand new part. Previously I verified that this issue persisted with a fresh OS X install. An external 4k display and USB and Thunderbolt storage devices were the only non-standard additions.

For those joining the thread late: Earlier in the thread, somebody mentioned that they were having luck as long as they remember to power off their external Dell display before letting the iMac go to sleep. A few others reported success, with one other still having the problem.

You might also take a moment to get a VNC app for your iPhone or iPad. RealVNC is one that's free. I see a good many other choices. Enable desktop sharing on your Mac and get that working now. Then you can at least log in with your phone and see your desktop when the display won't wake. I do this so I can cleanly exit programs and shut down. Basically I'm using my iPhone as an additional mirroring monitor temporarily. It's laggy as all get out, but it's better than hard power offs.

Well, I had this problem when I updated to 10.12.4 on 03/29 and I just did the 10.12.5 update and the problem is still there. A little recap of the original:

"when I come out of power saver (display off but computer running) the iMac screen stays dark. Well, almost. The screen comes on for a split second and then stays off. I have 2 4K monitors hooked up and they both come on like normal. "

I had been contacted by an AppeCare customer rep (Todd Seydel) who had me send in some files to the engineers at Apple to help them duplicate the problem. I had high hopes but to no avail. The problem still exists, and it in fact worse now than before. Instead of just the iMac monitor staying off and the 2 external monitors coming on only 1 monitor comes out of power save and the others stay off. Just thought I'd get this posted right away to let Apple know it's still not fixed. Hopefully this will be remedied with 10.13?

I also had this issue when updating from 10.12.4 on my 5k iMac. I updated yesterday to the official release of 10.12.5 and the problem still persists. I currently have a 28" Samsung 4k monitor that always turns on, but another LG 27" 4k will only turn on sometimes when waking monitors from sleep. When the LG doesn't turn on, the primary display on the iMac lowers it's resolution and switches sides with the Samsung monitor. The only solution I have found so far is to unplug the display port cable on the LG monitor and then plugging it back in to get it to work again. Occasionally the problem presents itself differently and both the Samsung and the LG monitors turn on at full resolution, but the iMac screen stays black and the only way to solve this is to restart the iMac.

Never had any issues previous to 10.12.4 related to the monitors not turning on after sleep or functioning properly. This has been a serious frustration ever since. It happens about every 5-10 times I put my screens to sleep, and I have to do that regularly with my job.

We need to open a new Thread as this has become a 10.12.5 bug and in my case is now more serious.

I had just updated to 10.12.5 16F73 and with 24 hours my system froze when I tried to wake it up while it was in screensaver mode.

The screensaver images froze on the two external monitors while the iMac monitor went black.

The system was unresponsive and I had to power cycle it.

I am looking forward to discussing this problem with Apple engineers at WWDC in a couple of weeks.

Also plan to put in another call to Apple support on this.

iMac (Retina 5K, 27-inch, Late 2015) + Acer B326HUL DisplayPort + Acer K272HUL DisplayPort

Cheers, Joe

Unfortunately this does affect Mac Minis. I have a Late 2012 2.6ghz Mini with 16gb ram attached to 2 Dell 24" displays - U2410 & U2413. I've literally done a bare bones reinstall of Sierra this morning and still get the black screen of death. This first started for me on 10.12.3 and still persists in 10.12.5

Things I've personally observed:

1. Mini boots to the U2410 (HDMI) but switches to U2413 (Thunderbolt to DisplayPort) in OS start up - this has always been the case regardless of version of Mac OS, but worth mentioning

2. Regardless of whatever else is plugged in to the other ports (USB, FW) after sleep for a prolonged period of time the U2413 display won't wake.

3. It seems to be a combination (in my case of which is the HDMI display - mine is U2410) if I swap the cables around U2413 works as expected

4. While disabling energy saving fixes the issue (as the displays never turn off) this is not a solution temporary or otherwise :(

5. Turning off the monitor and putting it to sleep does fix the issue (sometimes and only temporarily)

6. NVRAM & SMC resets appear to have no effect

7. My mini also does the primary display "flash" before falling in to a coma never to return

On a side not I have noticed that the primary display displays services starting up before the OS has fully booted (Dropbox etc) - so I can see the desktop briefly as a flash then it disappears again, while the actual log in sequence finalises.

My issue has been fixed with 10.12.5 - I can send my Mac to sleep again and the screen wakes up again.

The fact that the machine sometimes needs several tries to get the external screen running is still somewhat annoying

But in contrast to 10.12.4 it works somehow

Apple booked my iMac in for repair and identified an issue with 2 Ram cards. (I added 2x8Gb as soon as I bought the Mac in early 2016). I'd had no issues until 10.12.4 and it seems odd that an update could cause a RAM issue.

Anywho, removing the 2x8Gb slots does appear to have fixed the issue.

After a bit more playing I discovered that it seems to be related to (in my case) to Thunderbolt to Thunderbolt (mini DisplayPort), or Thunderbolt to DisplayPort combined with HDMI to HDMI (dual monitor setup). I switched the Thunderbolt connection to Thunderbolt to DVI (via the Apple Thunderbolt to DVI connector and all is working as expected - 4 days and counting without a reboot and wakes from sleep every time…

Admittedly this fix is for my Mac Mini, so not sure if the same change will resolve it for iMacs too (even just as a temporary fix)

Just did a simple test but my system did resume normally after the displays were turned off by Energy Saver under 10.12.5 on my iMac 5K + 2xAcer DisplayPort monitors.

Whether this holds long term, we shall see. If it doesn't, I still have my ticket to WWDC...

There are people on this group who took their iMac 5K's fresh out of the box and this sleep bug happened so the memory theory seems suspect (although maybe your RAM was marginal - I doubt it).

I did add memory to mine - as did many people - but this did not happen prior to 10.12.4 so this is something that Apple caused in their software update which impacted systems with and without expanded memory, not something that you caused by upgrading memory.

Another line of inquiry would be whether the new MacOS running 10.12.4 has problems with memory configurations (using anyone's memory, including Apple) of more than 16GB. I would not be surprised if someone in Cupertino left some code in there that assumed no configurations larger than 16GB which is the max in the MacBook line. So... is there anyone here who is experiencing the bug with a 4/8/12/16GB configuration? Anyone experiencing the bug who has not added memory? I suspect the answer to both questions is yes and yes.

Having said this, I ran an old iMac 12,2 with 32GB for 5 years with no problems through generations of MacOS before I got my iMac 5K last year. I immediately upgraded the 5K to 64GB and then also had no problems until 10.12.4 came out.

Good point about people who had the problem with a stock machine.

As an update:

iMac 27" 5K Retina (mid 2015)

8Gb RAM factory installed +

16Gb Crucial RAM that I added.

No problems until 10.12.4, then

-went to sleep when it shouldn't (set to 'never')

- whether manually or automatically in sleep mode, wouldn't wake

- could only start from sleep after unplugging power cable and waiting >5 mins

Apple repair service removed my 16Gb Crucial RAM. Problem gone.

I've just removed the 8Gb Apple RAM and replaced with the 16Gb Crucial RAM. Still working OK. In my case, it was clearly an issue with mixing different DIMMs.

According to the Crucial forums and Apple forums, a number of people have encountered problems mixing Apple RAM with other brands.

My guess is that whatever was included in 10.12.4 introduced new processes that triggered memory problems which hadn't manifested in previous versions.

To confuse matters, it may have also introduced other processes that affected other hardware components?

So, if you _do_ have a mix of Apple @ other memory, I'd definitely try that as a fix. For the rest of you, fingers crossed that Apple get their act together!