# Is there an index / explanation for Shutdown cause -63 in the system log?

I am using MacBookPro12,1 (early 2015 model) and it restarts randomly without any warning. In the log, I found this:

2017-12-14 20:51:50 Previous shutdown cause: 5 2017-12-15 10:37:31 Previous shutdown cause: 5 2017-12-15 12:08:05 Previous shutdown cause: -63 2017-12-15 19:14:19 Previous shutdown cause: 5 2017-12-15 19:42:05 Previous shutdown cause: 5 2017-12-15 20:09:32 Previous shutdown cause: 5 2017-12-15 22:32:39 Previous shutdown cause: -63 2017-12-16 00:08:00 Previous shutdown cause: -63

Any idea what might have caused it? I've looked up the cause code, but it didn't provide me any additional information and I couldn't find anything online.

UPDATE: Now I always get this shutdown problem after closing the lid and opening it again and logging in. It happens every time after 5-10 seconds of doing that.

• Negative numbers are usually hardware. I would start by running AHT (Apple Hardware Test). Hold D while booting from a powered off state with the AC cord attached. – Allan Dec 15 '17 at 19:56
• When I posted log lines like this a high rep user replied "I've never come across an issue with negative number 'shutdown cause' that wasn't fixed by repairing/replacing the Mac." apple.stackexchange.com/questions/134860/… – AllInOne Dec 15 '17 at 19:56
• Related, but doesn't explain what -63 is: Are OS X shutdown cause and sleep cause numbers listed/explained anywhere? – Alexander O'Mara Dec 15 '17 at 20:00
• @Allan I did run Apple Diagnostics. It didn't find anything wrong. I also did a full system recovery after erasing the HDD. What I noticed is that, it didn't happen during the recovery process which took several hours. After the recovery though, it started happening again, but only after immediately waking up from sleep/login. – Rajat Mondal Dec 15 '17 at 20:03