After a near-panic and interminable spin, it proved impossible to get useful diagnostic information. Here are some tools and techniques which should still be useful.
crash
Handling of kernel panics shows a series of fundamental flaws in El Capitan, which can occur on any Mac.
Was that crash a freeze, a panic, or just a spinning beachball? And what do they mean?
For the last 15 weeks, this iMac has been freezing sporadically. I have run out of ideas, and hope that 10.11.6 fixes the bug.
I may at last have found a way to reduce the frequency of freezing in OS X 10.11.4 and later.
After another system freeze, it is clear the problems in El Capitan are not fixed in 10.11.5.
Has your Mac been freezing occasionally since updating to OS X 10.11.4? You are not alone, it seems.
After a ‘Sleep Wake Failure’ and a bizarre ‘GPU Reset’, I’m not convinced that 10.11.4 is doing this iMac much good.
Things were not looking good: my Mac would not start up, and the RAID would not shut down. Stalemate.
When an app ran fine, but crashes in El Capitan, it may be SIP’s fault. Here is how to check, and more about SIP.
The Eclectic Light Company 