Thanks @fbara for suggestion to add more details
Device: MacBook Pro (Retina, 15-inch, Mid 2014)
OS: 10.11.6 (15G1004)
pmset -g log from one of the times it occurred
UUID: (null) 2016-09-07 20:15:11 -0700 Start powerd
process is started 2016-09-07 20:15:11 -0700
Summary- [System: No Assertions] Using Batt(Charge: 81) 2016-09-07
20:15:11 -0700 Assertions Kernel Idle sleep preventers:
IODisplayWrangler 2016-09-07 20:15:43 -0700 Assertions PID
104(hidd) Created UserIsActive
"com.apple.iohideventsystem.queue.tickle" 00:00:00 id:0x0x9000001f5
[System: PrevIdle DeclUser kDisp] 2016-09-07 20:16:52 -0700 Assertions
PID 261(Google Chrome) Created NoDisplaySleepAssertion "Playing
video" 00:00:00 id:0x0x500000223 [System: PrevIdle PrevDisp DeclUser
kDisp]
Best Answer
Please make sure you also check your Macbook for excessive dust inside!
I have a Macbook pro which shutdown randomly (and gave the shutdown cause -128 error, and also the reference code PPT004 - the battery requires service). When I cleaned the build up dust it started functioning normally again!
I just removed the backplate and used a can of compressed air to clean it. Check https://www.ifixit.com/Device/Mac_Laptop to see how you can remove the backplate of your model.
PS: Try not to touch any parts inside, because of static discharge