One of the Stack switch was rebooted WS-C3650-48TD.

[D RAVI KUMAR]

>> we have two switch connected as stack (WS-C3650-48TD)

>> Today we observed one of the Switch was rebooted automatically for unknown reason 

>>> After few minutes later SW-1 came up 

 we found below logs, Can any one check and let me know reason the switch was rebooted .

*Jan 9 01:18:04.279: %PLATFORM-6-HASTATUS: RP switchover, received chassis event to become active
*Jan 9 01:18:04.607: %HMANRP-6-HMAN_IOS_CHANNEL_INFO: HMAN-IOS channel event for switch 2: EMP_RELAY: Channel UP!
*Jan 9 01:18:04.684: %HMANRP-6-EMP_NO_ELECTION_INFO: Could not elect active EMP switch, setting emp active switch to 0: EMP_RELAY: Could not elect switch with mgmt port UP
*Jan 9 01:18:04.700: %REDUNDANCY-3-SWITCHOVER: RP switchover (PEER_NOT_PRESENT)
*Jan 9 01:18:04.701: %REDUNDANCY-3-SWITCHOVER: RP switchover (PEER_DOWN)
*Jan 9 01:18:04.702: %REDUNDANCY-3-SWITCHOVER: RP switchover (PEER_REDUNDANCY_STATE_CHANGE)
*Jan 9 01:18:04.736: %PLATFORM-6-HASTATUS: RP switchover, sent message became active. IOS is ready to switch to primary after chassis confirmation
*Jan 9 01:18:04.750: %PLATFORM-6-HASTATUS: RP switchover, received chassis event became active
*Jan 9 01:18:04.985: %PLATFORM-6-HASTATUS_DETAIL: RP switchover, received chassis event became active. Switch to primary (count 1)
*Jan 9 01:18:05.259: pm_port_em_recovery
*Jan 9 01:18:05.943: %HMANRP-5-CHASSIS_DOWN_EVENT: Chassis 1 gone DOWN!
*Jan 9 01:18:06.510: %LINK-3-UPDOWN: Interface Lsmpi19/0/3, changed state to up
*Jan 9 01:18:06.511: %LINK-3-UPDOWN: Interface EOBC19/0/1, changed state to up

[Leo Laohoo]

Post the complete output to the command "dir crashinfo-1:".

[balaji.bandi]

adding to @Leo Laohoo post, also it would nice to post show version

[karthikeyandrk]

Is it a single RPS or dual RPS? 
is it directly connected to raw power or through a UPS?

is those two switches connected to same power supply? 

i don't think so it was a HW failure or SW reasons, check for the power source first

[David Vasquez]

We just had this happen...Did you receive an explanation to the cause of the issue?

[padma]

I also had the same issue but with WS-C3850-48P-L running 16.6.4a code

[Leo Laohoo]

16.6.4a is not a "stable" code.
Post the complete output to the command "dir crashinfo-1:". Change the "1" to all the switch stack members.