[j-nsp] SRX300 Sudden Reboot

[Mohammad Khalil]

Greetings
I have SRX300 which is running normally for long time except for the last
two weeks where I have suffered from sudden reboot.
Model: srx300
Junos: 15.1X49-D70.3
JUNOS Software Release [15.1X49-D70.3]

Nothing has been changed or added and nothing in the log messages is
related to this.
As well , no active alrams and temperature levels are fine:
tbzadmin at FW-PB-NEW# run show chassis environment
Class Item                           Status     Measurement
Temp  Routing Engine                 OK         45 degrees C / 113 degrees F
      Routing Engine CPU             OK         58 degrees C / 136 degrees F
Power Power Supply 0                 OK

What could be the issue?

Much appreciated.