I upgraded Safari to version 6 on OS X Lion 10.7.4
The browser is really fast but with one problem, it keeps suddenly crashing and closing. Relaunching it wont prompt with the usual suspects: "Ignore" and "Report to Apple".
A common reason for an application crash is a corrupt preference file. The first thing you'll want to try is backing up and deleting your preference file for Safari.
Close Safari, and then you can find the preference file by going to
If that doesn't work, the next step would be to do a permissions repair using Disk Utility, which you can find in
Disappearance of Safari without a crash
The browser may disappear without crashing.
First, for the time of the disappearance, seek a matching
If you're using a proxy: this might be related to proxy settings in combination with WebSockets, as also noticed on Meta Stack Overflow. Though there it was reported for Mountain Lion, and it did show the option to send a crash report, and hence find some more details. Still then, maybe the symptoms are the same?
The blog post Networking Crashes In Mountain Lion and its comments blame crashes that refer to "CoreSchedulingSet::copyWithUpdatesReleaseSelf" to either the "Auto Proxy Discovery" and "Automatic Proxy Configuration" settings, or a VPN connection.
Some more investigation on 10.8, with only "Auto Proxy Discovery" enabled, without restarting Safari: