5k iMac reboots on it's own after installing 10.11.4

Got my machine back yesterday. New motherboard and power. I wiped the disk and installed 10.11.3 from my boot USB.

I've installed all my apps and settings. So far everything is running smooth and no reboots *crossing fingers* 😎

I bought the iMac 5k in december 2015. My friend erohne's iMac 5k is a couple of months newer.

What about the rest of you with 5k problems - is it also 5k "late 2015"-versions ?

Just a note that I also have the late 2015 27 Retina iMac, i7 4 ghz, Radeon M395X. Completely stable for months, from the time I purchased it (late November) until the installation of 10.11.4 update via the Mac App Store. Since 10.11.4, spontaneous reboots, usually at night when the computer has been idle for awhile, display is off. I am also seeing the -128 error code.

Seems pretty likely that this is an issue with this particular machine and 10.11.4 and not a hardware issue given that everything was stable before and there now seems to be a number of different people with the same machine reporting the same issue after installing 10.11.4. I've been going through the various attempts at remedies one by one, the last being a SMC reset this morning as the computer spontaneously rebooted yet again last night. My last attempt will be to reinstall via the combo updater, but not optimistic that will solve the issue. If everything else fails, will reinstall 10.11.3 from my time machine backup.

Hi,

my 5k-iMac is a late 2015 model too. I did a clean reinstall of OS X 10.11.3, cleared the nvram and reseted the smc but during the night, the imac rebooted itself again with a previous shutdown code of -128. So today i decided to call the apple support. First they asked my for a fresh installation and the typical trouble shooting steps. As i've told them that the proposed steps were already done, they told me to check if the issues consists, when i plug the power cable direct into the socket and not into a power strip.

The next step would be to bring the imac to an apple authorized service partner, but i don't believe that this issue is hardware related.

Has anyone found a solution for this problem, without hardware-replacement?

I have been experiencing the same problem. Just wanted to let you know that I have ZERO third party apps on my machine only Apple Software.

Like Terry, I have already posted on the "Unexpected reboots" thread and have had the selfsame problems.

My iMac delivered 1st December required a new screen within 45 days, so I was already worried about hardware QA issues. So having twice struggled to an Apple Store with the heavy box (I am 66 and not a spring chicken) and still having all the same issues as the rest of you, including restoring 10.11.3 and getting another two crashes within 24 hours, I am about to go back to Apple yet again for another telephone chat following yesterday's and no doubt another trudge to the Store.

I shall let you know if I get any further today, but after 30 years using Macs and never having had any quality problems whatsoever, this is a huge blow to my trust in Apple and their current direction concentrating on IOS and mobile and ignoring the desktop technical/professional/commercial market.

From my reckoning between the two threads there are at least a dozen of us affected and getting nowhere.

As a medical translator requiring a two document, double A4 screen for 24-hour turnaround, I can't afford to waste £1800 on something totally unreliable and a potential danger to my professional status, even if it is nice to have the huge retina screen for my photography hobby ...

Tim, Steve is watching you {:O))

Somebody on the other 'unexpected reboot' thread sent this message today:

wrfulton including Apple logo changes for feature 126 Apple image including Apple logo changes for feature 126 Apple image ends here

Apr 5, 2016 8:05 PM

in response to wrfulton

[DocumentBodyStart:56bffc1c-0cef-47c0-9943-c42271366b62]

It just occurred to me that when I took the iMac into the apple store for a fix they used a wired keyboard and wired mouse ( not my wireless keyboard and mouse ).

On the off-chance it make a difference I dug out an old wired keyboard and wired mouse and have restarted the iMac; I also turned off Bluetooth.

Hopefully this make a difference; will post tomorrow on how many unexpected reboots I get.

This was my reply:

-------------

I had a long conversation with a Senior Support Advisor and can call him back directly from now on.

Given my senior age, they agreed to collect my computer and use an Approved Repair Service provider rather than have to go through the Apple Store.

I discussed a lot of the issues others like yourselves have brought to light, and the opinion seems to be that it is hardware more than software, especially when I said I had restored 10.11.3 and still have the same problem - in fact 10.11.3 has just crashed out back to log-in THREE times in the last half hour.

Further to your comment above, I have a wireless magic trackpad 2 but a wired keyboard on my machine - the very odd thing is that not only does the keyboard freeze with the screen before the black reboot screen appears, but also the bluetooth connected trackpad - normally this has a physical movement and audible click, and only by moving the lock switch is this turned off. So the freeze must also turn off the physical mechanism via the bluetooth connection.

Certainly the Senior advisor and the service provider both asked me today about any connected peripherals. You may have a point, but I still think it is a more complex hardware issue and we are clutching at straws. See the other thread for the range of self-fixes already tried without success.

One commentator raised the idea of an AMD graphics fault which showed similar symptoms in a games machine he previously had with an AMD inside. Since I had a screen fault that was cured by fitting a new screen one month after buying this iMac, I have to wonder if the graphics connection might be an underlying cause, hence the odd times when the computer crashes but comes straight back to life from the black screen without requiring a log in - it is as if the screen had just given up with an overload of some kind and rebooted itself without affecting the main OS itself.

----------------

Anybody any ideas??

Regarding the screen fault that required a brand new display, the fault cannot have been 'dead' pixels.

The vertical bar that became permanent on the desktop/application screen view disappeared when the screensaver appeared!

Explanation anybody so we can discount any graphics/gpu involvement?

For a machine that performed without issue prior to the 10.11.4 update, there are only two reasons I can think of where a time machine restore wouldn't solve the problem: (1) picked the wrong date for the restore (not a 10.11.3 or earlier backup) or (2) 10.11.4 updated firmware in addition to software. In the past firmware updates have been separate from software updates but with Apple these days who knows... In any event, a time machine software restore to a prior version of the operating system will not roll back a firmware update as far as I know. It's software only.

My last attempt was resetting the SMC. Got just about 4 days of stable operation (with light machine use) before the dreaded spontaneous reboot happened again. Reinstalled 10.11.4 via the combo updater this morning, but not optimistic that will do any good. Next and last will be a time machine restore to 10.11.3

Notes: For me the reboots usually happen at night (or when the machine is unattended). So far it hasn't happened when the machine is in use. No issues with freezes. For the folks who have contacted Apple support and were offered replacement machines - good luck. There is absolutely nothing to indicate there is any hardware problem whatsoever, particularly when the most common trait that everyone seems to agree on is that there was no issue anytime prior to 10.11.4. Apple customer service is usually good and will bend over backwards to resolve customer issues, but the fact is that no one has reported that software (specifically the 10.11.4 update) has been unequivocally ruled out by Apple software engineers as the cause of the problem. Replacing a machine is the easy answer to a problem where you have basically no idea what the cause of the trouble is and the customer is happy because they get a brand new machine. Well until the next software update creates a problem. It's replace and pray. In event a brand new machine that arrives with 10.11.3 or earlier preinstalled should be fine. Just don't update it.

Well if I am reading this correctly - and that's a big if, I'm no expert - it looks like Apple did indeed update firmware in addition to software with 10.11.4 Taken from my /Library/Receipts/InstallHistory.plist

<key>date</key>

<date>2016-03-23T14:20:42Z</date>

<key>displayName</key>

<string>OS X El Capitan Update</string>

<key>displayVersion</key>

<string>10.11.4</string>

<key>packageIdentifiers</key>

<array>

<string>com.apple.pkg.update.os.10.11.4.15E65</string>

<string>com.apple.update.firmwareupdate</string>

</array>

<key>processName</key>

<string>softwareupdated</string>

So that might explain why a time machine restore from a backup that was stable prior to installing 10.11.4 still exhibits the same issue with unexpected restarts (and kind of points to the firmware update as the likely troublemaker) as a time machine restore will have no effect on firmware. At least that's my understanding. Unfortunately, if that's the case it will be entirely up to Apple to fix it whenever they get around to it.

In my case, Apple Authorised Repair guy phoned to say there was a logic board and power supply fault, replaced and now doing final testing.

Should have iMac back tomorrow.

Just like my friend DocLaban I also had to send my iMac in for repair, and they changed my mainboard too. Just got it back this afternoon and I've begun reinstalling all my software (I had to do a complete reinstall after the whole fusion disk got wiped clean after an unsuccessful TimeMachine rollback). I asked the service repair center about the power supply, but they said they didn't find anything faulty with it after having tested it extensively. They also said that even though both me and my friend DocLaban had the exact same reboot problems on two almost identical late 2015 iMac 27" 5K Retina machines, and they had to change mainboards on both our machines to solve the problem, there where no indications whatsoever or info from Apple that this was a known issue and problem with this line of iMacs. After having seen people around the world having the exact same problems, and others getting their mainboards and power supplies changed as well, I'm smelling a Retina-Gate scandal here....

Cheers,

Eivind

Hi @All,

i guess that the issue is triggered by a faulty firmware, that came with os x 10.11.4. This would explain why this issue came with 10.11.4 but won't be fixed by installing 10.11.3.

Since a few days the public beta of 10.11.5 is available - has anybody the chance to test if this would solve the problem with the random reboots?

I still can't believe that this is an hardware issues.

Just adding my name to the list of people having this exact same problem:

• Late 2015 Retina iMac 27inch, 4GHz i7 Radeon R9 M395X
• Computer completely stable until OSX 10.11.4 installed
• The computer now reboots several times a day, no pattern to what software/hardware is running
• Sometimes reboots when I am working on it (Bluetooth Magic Mouse freezes then reboot occurs)
• Sometimes reboots when idle - I hear the chime when watching TV etc
• No screen messages after reboot
• Have checked the console logs and found the same 'Previous shutdown cause: -128' being discussed on this thread.

Given that none of the things tried so far by everyone else seems to be working I suppose I will wait and see if OSX 10.11.5 helps.

*sigh* These computers are way too expensive for this **** to be happening...

I have same issue with 5k iMac purchased in January 2016. 4Ghz, Core i7, SSD, and AMD M395X. I thought it was related to Safari, since it was the only thing open during most of the restarts. Like one of the above posters, I am not running Safari so I can rule it out. It hasn't been often enough to be annoying and it reboots quickly. But given that it is a new machine and I didn't notice it until the 10.11.4 update, I'm going to keep track of the number of reboots. Haven't contacted support yet, wanted to research to see if anyone else having issues. I may wait for 10.11.5 too. Enough support calls/returns on same model machine will prompt Apple to take a closer look, i.e., if it is firmware/software related. I did diagnostic startup, with no issues found. There are no errors shown after these reboots either. I agree these iMacs are too expensive for these kinds of issues, given the Apple reputation.

I guess is another "me too" post...

Very same symptoms on my new iMac 5k. Sent it back to the authorised reseller and they cannot find anything wrong with the hardware or software. I'm not located in a country with an actual Apple Store so they don't just replace things. My only hope is that 10.11.5 will fix it and that it's not a hardware problem. Or perhaps Apple can release an official statement and if it does requires hardware changes, the authorised reseller will be forced to comply.

I had them put in 10.11.3 but it didn't make any difference. I guess I'll upgrade it now to 10.11.4 just to have the latest security updates. I do hope Apple is aware of this issue.