iMac (Retina 5K, 27-inch, Late 2015) Randomly Restarts Without Errors

Ummmm, yeah, saviorrisen, not trying to beat up on you, but don't really see what the point of that post is. OF COURSE most iMacs are not going to have this problem. If they did, it would be a national or even international story--ENTIRE GENERATION OF APPLE COMPUTERS LEMONS or something--and this thread would be thousands of pages long instead of just a couple dozen. I don't think anyone here is claiming that all iMacs are fatally flawed.

But this seems pretty incontrovertibly like a weird and specific problems that affects some subset of users of this generation of computer. I'm really happy for you that your computer is working, and I say that without any bitterness or sarcasm. Nonetheless, it doesn't change the fact that we're having this problem, and that it's a common enough problem that Apple should be aware of and have some solutions to it. Even if the pool of computers affected in this way is just a small subset of the overall pool of new iMacs, it still is obviously a problem that affects more than just one machine or two.

I spoke with the Apple Senior Advisor I've been working with this morning, and I feel as if finally (after a month) and lost productivity, time, and money (50 bucks down the drain to an Apple support tech Apple won't compensate me for), I may be getting somewhere.

The Senior Advisor contacted me, admitted it must be "frustrating to be dealing with this," and reached out to Apple's engineers with the promise that "I'm going to push them for a hardware fix, as at this stage, nothing software related seems to be working."

Already been down that road I wouldn't hold your breath. My senior advisor was so **** quick to jump to "Your aftermarket ram is probably the cause of your issues, or Senior Engineering team also said so." which is a bunch of BS. I'm contemplating not even taking it to the Apple store and wasting my **** time and rather might take it to a local Apple tech, since I have a feeling even though its within warranty they're probably going to charge me an arm and a leg to replace the logic board, because of the "Unapproved Apple Ram" crap, which has been in the machine right after unboxing.

They told me it was my third party RAM as well so I pulled it and the crashes continued. Then I pulled the Apple RAM and the crashes continued. I've been going around and around with Apple Support for three months now. I need to just give up and get to a service center but the closest one is an hour and a half away and I can't afford the downtime in my business to leave the computer for an extended time. That's why I purchased Apple Care, only to find out that there are apparently no service providers in my area to do in-home service. I had hoped Apple would find a fix in the meantime but I'm tired of dealing with the constant work interruptions.

Same exact thing here, pulled the RAM went back to the original and the restarts continued. The restarts only happen if I have either one or both of my external monitors plugged in, which tells me its gotta be a power supply issue or something up with the logic board not being able to handle the 4Ks.

Sorry you guys are having the same issues and frustrations! I do think however if you remain vigilant you'll get the hardware replacement you need. You'll need to hound Apple again and again until this happens––and I will until my iMac is completely fixed.

Apple's Engineers are now saying "It's your Thunderbolt display or Thunderbolt drive!" two devices that were powered off, but plugged into the back of my machine during the various restarts. Again, the engineers continue to point fingers at everything non-Apple.

Within minutes of unplugging those external accessories, guess what? Another freeze and shutdown. Same symptoms and error -128.

My Senior Advisor was like, "Perform another 'Capture App' without those devices plugged in and see what they say then––I am pushing as hard as I can for a hardware solution to your problem!"

Like most people here, my iMac 5k is my work machine, not a casual email/word processing computer, so these constant "uninstall this, unplug that" requests in addition to never knowing when my machine may randomly restart on me is a huge problem for my business.

I told my Senior Advisor that I had to reinstall Adobe software on the machine today, after uninstalling it at the bequest of the engineers over the weekend so they could see if the restarts occurred without Adobe or Chrome software on the system. The iMac 5k restarted almost immediately Friday and Saturday after uninstalling these apps. So, Adobe and Chrome are not the problem.

But because I need Adobe software for the work I need to do on this machine this week, I reinstalled Creative Cloud and made sure to notify my Senior Advisor and ask him to tell the engineers:

"Hey, we already tried uninstalling Adobe and it had no impact on the restarts"

I did this to make sure the engineers don't somehow forget and blame Adobe again (and thus extend this drama even longer without a fix).

That may sound crazy, but with the sheer # of cases I assume these engineers work on, and their track record thus far on my case, I'm not hugely confident that there's enough communication going on that they may round trip to their "it's Adobe's fault!" conclusion again.

The bottom line that I'm trying to convey to Apple is, none of these applications are at fault––it is almost certainly a Apple hardware problem, and I know this because when I completely wiped the hard drive and restored the OS to the dreaded 10.11.5, not installing any non-native apps, the restarts continued unabated. And Time Machine-ing back to 10.11.3 didn't solve the problem either.

Now getting the Apple engineers to investigate something other than 3rd party applications or accessories is the frustrating part and feels like pulling teeth. I can only imagine that they don't have an immediate solution, hence this weeks long back and forth.

I watched the last restart carefully. The clock was at 15:40:14 and froze at that time for about 25 seconds. I caught it because the song I was listening to in ITunes just cut out. Mouse and Key Board unresponsive. The log had nothing in it at that moment. In fact it had nothing logged until the reboot at 15:42:10 Boot_. Prior to that the last log entry was at 15:34:18 - something about Bluetooth -yada, yada. So at the actual restart there was nothing happening software wise - according to the log. I set the seconds on the clock to see if the system indeed freezes up completely and it does. Everything stops working right before the restart.

It is a major malfunction - hardware related?

3 months on the Apple Merry-Go-Round - no resolution.

Same here, absolutely no errors in the logs. Which tells me its gotta be hardware related something with the logic board is what most are saying. I'm taking mine to a local shop (forget dealing with Apple, can't have my machine gone for more than the weekend) and I'll post back my findings.

Bought refurbished 27 i5 iMac Retina etc from Apple on June 22, and it is randomly restarting once or twice a day even after update to 10.11.6. It seems there is no answer yet. I would return it, but then I lose several days and no guarantee that the replacement wouldn't have same problem.

Hey there mrdgvb1. I was just wondering where do you find these logs?

Go to the Magnifying Glass on top right of screen. Click on it. Type in: Console. Logs will appear.

Hi folks - another "me too" post.

I've been having these issues since installing 10.11.4 but neither 10.11.5 or 10.11.6 have resolved the hang/restarts.

Every update I've done uses the "Combo Updater" as a matter of course.

I presume this is related to the issue that affected the MacBook Pro community (http://forums.macrumors.com/threads/macbook-pro-2015-with-osx-el-capitan-10-11-4 -system-wide-freeze-read-the-details.196…) but that seems to have been addressed in 10.11.5 unlike ours?

My machine is due for a Genius Bar visit after exhausting all of the debug steps I could think of:

• Zapped PRAM
• Safe Boot
• Reset System Management Controller
• Diagnostics boot - no problems found
• Disk first aid from Recovery partition - no problems found
• 3rd Party RAM removed
• MemTest86 (four complete passes) - no problems found

iMac (Retina 5K, 27-inch, Late 2015)

Mac OS X El Capitan 10.11.6 (15G31)

Memory 8 GB 1867 MHz DDR3

Graphics AMD Radeon R9 M395X 4096 MB

Serial Number DGKQL068GQ17

Cheers

Mike

Hi bendean.

When you said "...and performed Capture.App of data from the Mac..." can you explain what that app is / where it comes from / how to use it? I can't find it on my machine to try to see the same information from my own setup.

I looked everywhere, as root - so I'm missing something for sure:

Mikes-2015-iMac:/ michthom$ sudo bash

Password:

bash-3.2# find / -xdev -iname capture.app -print

bash-3.2#

Took my unit to local Apple authorized service dealer, they did all diagnostics and did clean install, but it did a random quit once I got it back. It seems no one knows cause of this problem. I wonder if Apple will swap out my machine if I send it back. Very frustrating, never had this kind of problem with any Apple software or hardware.

An update on my iMac:

They changed the logic board. No restarts since then.

My advice to any of you having the same problem is this:

1. Ensure you are experiencing the same issue. You have to be 100% sure. If your computer randomly freezes, then restarts, with no errors other than a "Previous shutdown case: -128" in the console, then you have the same problem.

If your computer shutdowns without restarting or your issue varies in someway, I recommend you to assume it's not the same cause/problem.

2. Talk to AppleCare and describe your problem. If they don't suggest it to you, tell them you are taking your computer to an authorized repair center.

3. Wipe your hard drive clean, except for the Recovery Partition, and take the iMac to the repair center. Describe the problem to the person that receives the computer, emphasizing that the reboot is not triggered by heavy load and that they should look for the "-128" message in the console.

4. Once it is undergoing the tests, call the repair center and remind them that the best clue that the reboot happened is the "-128" message in the console, and that when it reboots, it automatically reopens the apps that were running, so the computer has to be actively monitored or that they should disable auto-login, so they can notice a reboot happened. If possible, try to talk with the exact person that is actually conducting the tests on your machine.

After they end their test they should:

-See no errors in the Apple Hardware tests

-See no apparent malfunction in the hardware (ensure that they open the computer and check the insides)

-Have it very clear that software is not at fault

I cannot guarantee that you'll get your logic board replaced, but they should have no other option.