Almost every morning, Safari quits unexpectedly. This seems to happen only once a day and it doesn't matter whether I've used it since opening the computer or not. (I leave apps open overnight and just open the lid to start working again.) Here are a couple of days' console outputs around this event:

2015-08-16 7:21:28.359 AM lsboxd[285]: @AE relay 4755524c:4755524c
2015-08-16 7:29:12.336 AM com.apple.launchd[1]: (com.apple.XType.FontHelper[2321]) Exited: Killed: 9
2015-08-16 7:29:12.000 AM kernel[0]: memorystatus_thread: idle exiting pid 2321 [XType.FontHelper]
2015-08-16 7:29:12.638 AM com.apple.launchd.peruser.502[142]: (com.apple.pbs[2310]) Exited: Killed: 9
2015-08-16 7:29:12.000 AM kernel[0]: memorystatus_thread: idle exiting pid 2310 [pbs]
2015-08-16 7:30:54.856 AM com.apple.launchd.peruser.502[142]: ([0x0-0x27027].com.apple.Safari[316]) Exited: Killed: 9
2015-08-16 7:31:14.702 AM com.apple.launchd[1]: (com.apple.coremedia.videodecoder[1872]) Exit timeout elapsed (20 seconds). Killing
2015-08-16 7:31:25.534 AM com.apple.usbmuxd[21]: stopping.
2015-08-16 7:31:25.784 AM com.apple.usbmuxd[2356]: usbmuxd-345.70 on Jan 26 2015 at 16:55:11, running 64 bit
2015-08-16 7:34:04.188 AM WindowServer[84]: Created shield window 0x333 for display 0x04272780

2015-08-19 6:54:55.976 AM com.apple.launchd.peruser.502[142]: ([0x0-0xa7ba7b].com.apple.inputmethod.ironwood[5854]) Exited: Killed: 9
2015-08-19 6:54:56.000 AM kernel[0]: memorystatus_thread: idle exiting pid 5854 [DictationIM]
2015-08-19 6:54:56.595 AM com.apple.launchd.peruser.502[142]: (com.apple.CalendarAgent[5792]) Exited: Killed: 9
2015-08-19 6:54:56.000 AM kernel[0]: memorystatus_thread: idle exiting pid 5792 [CalendarAgent]
2015-08-19 6:54:57.415 AM com.apple.launchd[1]: (com.apple.sleepservicesd[5781]) Exited: Killed: 9
2015-08-19 6:54:57.000 AM kernel[0]: memorystatus_thread: idle exiting pid 5781 [SleepServicesD]
2015-08-19 6:54:58.000 AM kernel[0]: memorystatus_thread: idle exiting pid 5786 [cfprefsd]
2015-08-19 6:54:59.693 AM locationd[6000]: NOTICE,Location icon should now be in state 0
2015-08-19 6:54:59.879 AM com.apple.time[145]: Interval maximum value is 946100000 seconds (specified value: 9223372036854775807).
2015-08-19 6:56:43.388 AM com.apple.launchd.peruser.502[142]: ([0x0-0x938938].com.apple.Safari[5308]) Exited: Killed: 9
2015-08-19 6:57:16.000 AM kernel[0]: (default pager): [KERNEL]: default_pager_backing_store_monitor - send LO_WAT_ALERT
2015-08-19 6:57:21.000 AM kernel[0]: macx_swapoff SUCCESS
2015-08-19 6:59:47.924 AM WindowServer[84]: Created shield window 0xb9f for display 0x04272780
2015-08-19 6:59:47.924 AM WindowServer[84]: device_generate_desktop_screenshot: authw 0x0(0), shield 0x0(0)
2015-08-19 6:59:47.935 AM WindowServer[84]: device_generate_lock_screen_screenshot: authw 0x0(0), shield 0x0(0)

Any suggestions? This is Safari 6.2.7 on a 2009 MacBookPro using OS 10.8.5

Thanks, Eleanor

it looks like its being KILLED, not "quitting unexpectedly" (crashing).... what's killing it?

Can't help...sorry, but welcome to FineTunedMac.

See this Apple Discussion

Thanks for this reference, but it doesn't match my symptoms well, and the solution here is pretty drastic, so I'll hope for a more enlightening diagnosis.

Good question!

I am the same version of Safari and OS as you, except my machine is an older Intel iMac.

The last while, maybe a couple of weeks, Safari has occasionally unexpectedly quit, although I am not certain that it would be every day. My routine is a bit different from yours. I do not leave my machine on all night - I log out, put the machine in sleep mode, and log in.

However, for the 'unexpectedly quit' events I recall the dialogue box had an odd message. It was something like "Safari content has unexpectedly….". Do you get a message like that?

Safari 6.2.8 is now released and I see that one of the things it addresses is 'stability'. I wonder if the update will help….sure can't hurt.