I think I've hit the end of the road trying to update my MBP 2011. I tried to restart to apply the last security update and my system consistently panics with the following error:
*** Panic Report ***
panic(cpu 6 caller 0xffffff7f863d98d7): "GPU Panic: mux-regs 2 3 7f 0 0 0 severity 3 WS-ready 1 switch-state 0 IG FBs 1 EG FBs 0:0 power-state 3 3D idle HDA idle system-state 1 power-level 20:20 connect-change 0 : AGC GPU REGISTER RESTORE FAILED : rdar://7254528, VendorID invalid\n"@/BuildRoot/Library/Caches/com.apple.xbs/Sources/AppleGraphicsControl/AppleGraphicsControl-3.20.15/src/AppleMuxControl/kext/GPUPanic.cpp:170
Has anyone seen this?