10.12.4 display sleep bug

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!

The display sleep bug returned on my system iMac 5K + 2xAcer DisplayPort monitors after about 24 hours unfortunately.

I have my ticket to WWDC so I'm going to have a chat with some MacOS folks there.

Maybe this will be fixed with MacOS Petaluma ;-)

Meanwhile back to never sleeping or just shutting down the system. At least with the SSD the system boots fast.

It is a bad idea (on any system) to mix memory brands - have even seen this kind of problem with Dells.

But I would postulate that most of the people posting here have memory either all from Apple (from the box) or all from a third-party like Crucial or MacSales since when you go third-party, you usually buy a minimum RAM configuration and upgrade all 4 slots.

Also, Mort, it sounds like you had a different problem since with the classic display sleep bug, the system does wake up but the iMac monitor doesn't turn back on. The other monitors may or may not turn back on (I just had it happen this morning and one of my external monitors came back on).

Earlier in the thread, binaryage said the first beta (10.12.6-16G8c, or 10.12.6-beta1) had not fixed the issue. Typically there are multiple releases of each beta. It's still possible that a subsequent 10.12.6 beta release will contain a fix.

So everybody knows: The priority of this fix will be driven by how much press it gets, and how many users create support tickets with Apple. Press on an issue like this is unlikely, but if you have AppleCare or are still in warranty, please be sure to create a support ticket with Apple and point to this thread. You can do that by phone or email on Apple's support site. If the support organization says this issue causes frequent contact from the users, the engineering leads will raise the priority.

As things stand, the couple people who have written about reaching out to Apple Support were told that Apple wasn't aware of this issue. The callers were put through the standard reinstall, reset controller, etc troubleshooting.

It's a terrible state of affairs when something as basic as external monitor use is unreliable.

I wish my 5k iMac was still under warranty. This bug is so frustrating. I want to report it, but don't know where. Either one of my 4k external monitors does not come back on, or the primary iMac display does not come back on after putting the screens to sleep. I can unplug the 4k and plug it back in to reset it, but nothing short of rebooting will fix the primary display. For such an expensive piece of hardware, this seems like a major bug. I have to reboot my computer at least once a day, and have to re-seat the 4k monitor display port cable several times. It definitely started happening in 10.12.4 and appears to have become a more frequent issue in 10.12.5 for me. I really hope this gets fixed!

With respect to "where" to report this bug, if you have an Apple developer account, you can log into the Apple Bug Reporter and report the bug. I met with an engineer at WWDC and he recommended doing a sysdiagnose when it is in the dark iMac monitor state and attaching that to the bug report. He took a quick look at the bug report database and couldn't find this problem so it is possible that no one was entered it (please reply if you have and have a bug report case number because I could bring that to an Engineer at WWDC today). He said that the AppleCare / Warranty channel is buffered too much from Engineering and that the best route was direct to the Bug Reporter.

The command-line utility

sysdiagnose

The issue still persists with the latest developer builds. I had rang Apple Australia about a month ago and was told Engineering was made aware of this issue. Further my previous post which expressed my displeasure with Apple was censored / removed. Not impressed that an expensive computer has such poor support. Not impressed at all!

This issue has been resolved for me, but I don't know how.

iMac Retina 5K, 27-inch, Late 2015 - macOS 10.12.5 (problem appeared after installing 10.12.4)

AMD Radeon R9 M395X 4096 MB

40 GB RAM (2 x 4GB from Apple + 2 x 16GB from OWC)

2 additional 4K Samsung U24E590 displays

I was getting ready to file a bug report as hmbay suggested, and performed the following steps:

1. Ran sysdiagnose with the system working (i.e. all displays working properly) with energy saver preferences as follows:

* Turn display off after - Never

2. Changed energy saver preferences as follows:

* Turn display off after - 10 minutes

* Prevent computer from sleeping - Unchecked

3. Waited until the computer went to sleep, then woke it up with the plan to run sysdiagnose again with the main display off... but the main display (and the two external displays) came on as they should.

The iMac has been working correctly for 4 days now.

The problem with this is (as far as I know) most of us have had the problem with just the displays going into sleep, not the iMac. Try selecting the "Prevent computer from sleeping" option and see if it happens. That is how my iMac was configured when I got the issue here. Displays turned off after x number of minutes and prevent computer from sleeping. Every time I try to wake the displays up only 1 or 2 of them come back but never all 3. This requires a reboot.

I just changed Prevent computer from sleeping to Checked and put the displays to sleep (by using a hot corner). All three displays came back as they should.

Unchecked the option again, put the computer to sleep and woke it up. All three displays came back.

The problem with my iMac had always been with the main display, and only a few times one (random) of the external displays. Most of the times both external displays came on, but the main display was always black after going to sleep.

Most times I was able to see the lock screen for a brief moment (one second or so), before the main display turned off and I had to reboot in order to be able to use it again.

Now that the problem is not happening, I have noticed that both external displays take a few extra seconds to turn on. One time it was long enough for the OS to move all windows from one external display to the main display.

I have monitored the Console before to try to find a log entry that could offer a hint about this problem, but there's nothing meaningful.