PS4 software update 2.01 rolling out today, will address rest mode issue
PS4 firmware 2.0 Masamune has introduced a pretty nasty problem, but happily there's another one on the way which will hopefully fix it.
The latest PlayStation 4 system software update has caused problems with rest mode.
UPDATE: Sony Europe just confirmed on Twitter that firmware 2.01 is rolling out today.
Original Story: Sony acknowledged general issues with the firmware update when reports first arose, but in a tweet today acknowledged the rest mode problem in particular, saying a fix is inbound.
The rest mode issue is quite serious as it requires a hard reset to recover from, which can be very risky; you may end up wiping system data or worse: bricking the console.
Best to switch your console off completely between sessions until the next firmware update; pull the plug out the wall, even, and save yourself some energy bills.