This question is def. not a duplicate of the ones linked. "Your Battery is Dead", I'm afraid, is not the solution.
Edit: The event did not happen with AC plugged in, it happened on battery. I then plugged in the AC in order to wake it. The battery is fine and does not need replacement.
So I woke my MBP from sleep, plugged in my iPhone and within a minute, computer put itself back to sleep. I plugged the AC in, woke it up and checked the logs. The offending message is the title of this Q.
My battery has gone through about 926 cycles, so not exactly dead. Couldn't for the life of me figure out what had happened, but I run Micro Snitch in the background, which happened to be telling me that a microphone had kept getting connected/disconnected.
Well, at that point, I quickly realized that the Apple Lightning to USB adapter I plugged in was faulty and constantly cycling on/off, thus throwing my machine into disarray, as Photos and iTunes are set to open automatically when my phone is attached.
I'm guessing that the algorithm used to determine "remaining charge" decided that if my laptop kept doing what it was doing, the battery would very quickly die, so it put itself to sleep.
Of course, I could be wrong.
My question is, does anyone know where I can look to verify this (or what) happened, exactly? 'Low Power Sleep' isn't exactly an error, so my guess is this would be logged as an ordinary event.
Here is current battery info:
Charge Remaining (mAh): 4893 Fully Charged: No Charging: Yes Full Charge Capacity (mAh): 7426 Cycle Count: 926 Condition: Normal Battery Installed: Yes Amperage (mA): 3586 Voltage (mV): 12436