Today, Aug 3 I did Security Update 2019-004. (without reading about it on internet, my bad)
Alarmingly, this kernel panic on load from clover screen after the start of the update process.
Sierra bootst in Safe mode (hit space bar and select at clover screen) and run.
It would also boot recovery mode, but Time Machine seems unresponsive when trying to restore OS.
Tried to boot normally and have the same kernel panic. Will start separate post if I do not fix this evening.
Not sure why this update from App Store failed in this way on my machine, i.e. That is is or is not related to general reports of kernel panic from the 2019-004 and that Apple pulled it.
Update--- if 2019-004 is reapplied in 'Safe' mode, and the computer shut down , it will boot normally just once. It will sleep and wake. However, if it is rebooted a second time it KP's until run in Safe Mode and the 2019-004 reapplied again. Suspect some kext is in need of modification, or....??? Working on it. Might have to reinstall OS X.