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

Does it completely shut down and restart with a chime, or does it just log you out?

Please search the log for the text "Previous shutdown." What do you find?

A negative shutdown code may indicate a hardware problem. The precise meaning of the codes is not publicly documented. They are not the same as error codes.

If you haven't already done so, you can try resetting the System Management Controller. Otherwise, or if the reset has no effect, see below.

Make a "Genius" appointment at an Apple Store, or go to another authorized service provider. You may have to leave the machine there for several days.

Back up all data on the internal drive(s) before you hand over your computer to anyone. There are ways to back up a computer that isn't fully functional—ask if you need guidance.

If privacy is a concern, erase the data partition(s) with the option to write zeros* (do this only if you have at least two complete, independent backups, and you know how to restore to an empty drive from any of them.) Don’t erase the recovery partition, if present.

Keeping your confidential data secure during hardware repair

Apple also recommends that you deauthorize a device in the iTunes Store before having it serviced.

*An SSD doesn't need to be zeroed.

hey there

im experiencing random restarts with a chime and i have no clue what to do.

Screen goes black for a second and then there's the chime and back to the login screen... the whole process may last around 2-3 seconds but i dont think its normal.

I bought my imac 5k retina 2 months ago with the default hardware.

Any idea what to do?

Apologies in advance if it's inappropriate to post log output.

I will remove if it is a problem.

I'm also having the same issue on my 5K iMac.  Random Reboots sometime multiple times a day. Occurring after updated to 10.11.4

I've clear PRAM and SMC.

I have also reinstalled OS X.  Complete reinstall erased drive.

Issue still persists.

-128 SHUTDOWN CODE

Here is some output regarding how frequently the reboot occur:

last reboot

reboot    ~                        Wed Mar 30 18:24

reboot    ~                        Tue Mar 29 22:45

reboot    ~                        Tue Mar 29 20:06

reboot    ~                        Tue Mar 29 09:30

reboot    ~                        Mon Mar 28 23:00

reboot    ~                        Mon Mar 28 12:11

reboot    ~                        Sun Mar 27 19:10

reboot    ~                        Sun Mar 27 09:20

reboot    ~                        Sat Mar 26 19:39

reboot    ~                        Sat Mar 26 10:13

reboot    ~                        Sat Mar 26 09:44

I've looked through console can't pinpoint an exact cause.

At first this error was corresponding right before each reboot:

CalendarAgent[413]: [com.apple.calendar.store.log.caldav.coredav] [Refusing to parse response to PROPPATCH because of content-type: [text/plain; charset="utf-8"].]

I removed all calendar accounts to see if that was the cause.

It seemed to help the issue a bit because only 1 reboot so far today. But had another one while AFK at 6:24pm.

Here is the console output from the 6:24pm reboot:

Mar 30 18:18:28 Kurama identityservicesd[240]: <IMMacNotificationCenterManager: 0x7fdc43c569f0>: notification observer: com.apple.iChat   notification: __CFNotification 0x7fdc43d6bdf0 {name = _NSDoNotDisturbEnabledNotification}

Mar 30 18:18:28 Kurama imagent[291]: <IMMacNotificationCenterManager: 0x7fc9b1e2d470>: notification observer: com.apple.FaceTime   notification: __CFNotification 0x7fc9b1e90a90 {name = _NSDoNotDisturbEnabledNotification}

Mar 30 18:18:28 Kurama identityservicesd[240]: <IMMacNotificationCenterManager: 0x7fdc43c569f0>:    NC Disabled: NO

Mar 30 18:18:28 Kurama imagent[291]: <IMMacNotificationCenterManager: 0x7fc9b1e2d470>:    NC Disabled: NO

Mar 30 18:18:28 Kurama sharingd[268]: 18:18:28.130 : Purged contact hashes

Mar 30 18:18:28 Kurama sharingd[268]: 18:18:28.130 : Discoverable mode changed to Off

Mar 30 18:18:28 Kurama sharingd[268]: 18:18:28.130 : BTLE scanning stopped

Mar 30 18:18:28 Kurama identityservicesd[240]: <IMMacNotificationCenterManager: 0x7fdc43c569f0>:   DND Enabled: YES

Mar 30 18:18:28 Kurama imagent[291]: <IMMacNotificationCenterManager: 0x7fc9b1e2d470>:   DND Enabled: YES

Mar 30 18:18:28 Kurama imagent[291]: <IMMacNotificationCenterManager: 0x7fc9b1e2d470>: Updating enabled: NO   (Topics: (

Mar 30 18:18:28 Kurama identityservicesd[240]: <IMMacNotificationCenterManager: 0x7fdc43c569f0>: Updating enabled: NO   (Topics: (

Mar 30 18:18:28 Kurama identityservicesd[240]: <IMMacNotificationCenterManager: 0x7fdc43e68240>: notification observer: com.apple.iChat   notification: __CFNotification 0x7fdc43d66200 {name = _NSDoNotDisturbEnabledNotification}

Mar 30 18:18:28 Kurama identityservicesd[240]: <IMMacNotificationCenterManager: 0x7fdc43e68240>:    NC Disabled: NO

Mar 30 18:18:28 Kurama identityservicesd[240]: <IMMacNotificationCenterManager: 0x7fdc43e68240>:   DND Enabled: YES

Mar 30 18:18:28 Kurama identityservicesd[240]: <IMMacNotificationCenterManager: 0x7fdc43e68240>: Updating enabled: NO   (Topics: (

Mar 30 18:18:28 Kurama WindowServer[162]: device_generate_desktop_screenshot: authw 0x7fea14820400(2000), shield 0x7fea14853a00(2001)

Mar 30 18:18:28 Kurama WindowServer[162]: device_generate_lock_screen_screenshot: authw 0x7fea14820400(2000)[0, 0, 0, 0] shield 0x7fea14853a00(2001), dev [2560,1440]

Mar 30 18:18:28 Kurama WindowServer[162]: no sleep images for WillPowerOffWithImages

Mar 30 18:22:07 Kurama syslogd[40]: ASL Sender Statistics

Mar 30 18:24:52 localhost bootlog[0]: BOOT_TIME 1459376692 0

I have not reached out to apple support as of yet.

Thoughts?

Got done with Apple Support.

Escalated my case, but didn't really get closure.

They couldn't tell me what -128 code represented other than their resources led them down troubleshooting kernel panics.

However, I had completed their troubleshooting steps prior to the call because I referenced this thread.

So......

They asked me to remove all 3rd party applications because of interoperability with new updates.

I get it...but still a canned answer.  I also said the same 3rd party apps are installed on my Macbook Pro so not sure if directly relevant.

Also performed Apple Diagnostic Hardware test.  No issues were found.

Short answer...uninstall all the things and see if it happens again.  /sigh

Anyways, lets entertain them and maybe it is a third party app.

I have the following installed since my last reinstall.

Chrome

VLC

Transmission

TeamViewer

DropBox

Spotify

Flash (dun dun dun)

Anything match others who are having issues?

This isn't my primary machine so to test I have uninstalled all things as asked.

I'll let you know if the issue persists.