10.12.4 display sleep bug

Well that didn't work :-(

Returned (again) for repair, and stress testing showed problems with power supply & logic board. Now been advised that these are being replaced, so fingers crossed when I get it back.

Hope all goes well for you. I don't think this issue is a hardware problem considering the massive amount of people that started experiencing it after the 10.12.4 update. It's been months for me and Apple still has no answers. I have emailed the support guy recently and they will NOT even respond anymore.

Thanks, Apple!!! Way to go with supporting your customers...

I know it's commonly cited but rarely proven, but something tells me this may be one of those flukey occasions where a software issue has caused a hardware problem.

*If* 10.12.4 was routing too much power and/or heat to the GPU or part of the logic board, that might explain issues with either display failures/errors or random shutdowns. It would also explain why rewinding back to earlier versions or installing subsequent updates (19.12.5 & 6) fail to resolve the issue.

On the plus side, because I'm in the EU (for now, until Brexit kicks in), Apple have had to pick up the £780 tab for the new logic boand & PSU.

@Mort - Who has said that rolling back didn't fix the problem? Rolling back fixed it on two machines here. We're keeping those two systems unpatched and off the internet so they can continue with multiple heads.

Problem still persist with the 10.12.6 but at first it seemed fixed. However, if either of my identical setups (5k i7 32Gb + Dell 4k) is asleep, say over night, then it is seemingly random if the machine wakes up.

Apple is so slow to fix this that I have; 1) banned Apple purchases in my lab (I am the head) and 2) purchased 8 HP desktops (these actually work!).

Yes, the problem will manifest itself more with an overnight sleep. It's almost like there are multiple levels of power saving stages and once it's been sleeping for a while it enters that last stage where the problem appears to manifest itself the most. I too have a 5k, i7 32gb + 2 Samsung 4K's.

It's extremely troubling to have to deal with this issue on a daily basis, Apple needs to put some effort into getting this fixed!

I originally had this issue with a 2015 iMac 5K and Dell 24" 4K. I recently purchased the 2017 iMac 5K. With 10.12.6 and the same Dell 24" 4K, the problem persists but does seem to occur less often with 10.12.6. I continue to use my workaround of turning off the Dell monitor before putting the iMac to sleep but that's annoying to do. I'm going to attempt to use a different external monitor to see if it has the same issue. If I change the iMac and the external monitor and the problem persists, there's really nothing more I can do. Its up to Apple.

I've spent the last few hours downgrading to 10.12.3. The migration assistant worked fine apart from an issue with the Mac Mail database which required me to move my email out of the appropriate folder, fire up Mail, then copy over selected files (pretty much everything apart from the envelope files) and rebuild the mailboxes.

Not ideal being 3 minor releases behind but having two monitors is more useful than one and bug fixes. Although I will review what I'm missing out on just in case.

Not sure about the etiquette of closing a bug by saying it's a duplicate of a report I can't see because it's on someone else's account. Hopefully the system will tell me when they've figured things out.

So. . .

Apple care asked me to reset this that and the other, then wipe and reinstall OS. Problem persists

Repair #1 memory problems blamed. Returned to original Apple RAM. Passed testing. Problem persists

Apple Care advise resetting everything & reinstalling OS. Problem persists.

Repair #2 Replaced Logic Board & PSU. Passed testing.Problem persists

Now Apple Care advising me to reinstall OS.

I've had enough. Apple have had about £1800 off me for this iMac alone (about £6K across all my Apple devices).

Time to insist on on a replacement machine, I think. Very not happy!

I don't think a replacement will help you. This is pure and simple, it's a software bug! I have programmed enough systems in my day to know what is usually a hardware bug and what is software. This is a software bug!!!

Man, I miss Steve. Maybe if he was still around we would not even have this issue in the first place!

Something interesting I found during some experimentation. I have a lock screen which is password protected and when the iMac comes out of sleep mode is when the issue happens with monitors. I found that clicking the magic mouse to wake the system and entering the password immediately upon seeing the iMac screen come to life regardless of whether I can see the password field or not seems to work 90% of the time. It will usually flash the main screen once then all monitors come on equally. I have noticed also that this seems to prevent the second blackout which is usually the deadly one that causes the issues that only a reboot will fix. This may be an issue with the lock screen coming out of sleep mode. I'm going to try disabling the lock screen to see if it makes a difference. Just a wild thought and some experimentation to pass along!

No, Apple will no longer return my emails after several worthless attempts to fix the issue with my machine. I am seriously upset with Apple over this and it will definitely affect my future Mac purchases.

Apple obviously does not care about this issue and I believe there is NO attempt or initiative to fix the problem.

Like everyone else here, I have the same problem.

The only thing that's been working for me is each day, I go into Energy Saver, uncheck "Prevent computer from sleeping automatically when the display is off", leave Energy Saver, go back into it and re-check it again. Since I've been doing that each morning after waking the screens, (5 weeks? except weekends), the problem has only returned once (see below). I'm unsure if leaving Energy Saver is a needed step but it's working for me.

At one point during this time, I neglected to perform my routine, and within about 4 days, the bug happened again. Since I started it again, it hasn't returned.

From my investigation, clicking on that checkbox modifies the sleep time in minutes. Clicking on it effectively calls "

pmset sleep 0"

pmset sleep [value of the 'Turn display off after' slider]".

So, if I have turn display off after 3 hrs, set, and have "Prevent computer from sleeping automatically when the display is off" checked, it's effectively the same as saying "

pmset sleep 180

I've thought about attempting to create an automated solution to do this daily (ie cron job calling I think

sudo pmset sleep [time in minutes]

I have no idea how/if this could correlate to stopping the bug but at a minimum, clicking on the checkbox daily works for me.

The only other thing worth noting is my Mac is using Carbon Copy Cloner which wakes the displays each day at 5AM. Usually, the displays are still operational by the time I get behind my computer - within the 3 hr timeout).

Thanks for the info, in the end, Apple needs to really step up and fix this issue. Not so sure that will happen. I can only hope that High Sierra will fix the issue but may also introduce new ones at the same time. There is no doubt that this bug was introduced in 10.12.4 and it relates to the energy saver code but the fix would ultimately have to come from Apple!