Inflight sudden disarm and crash. Want to know why. Fixed-wing

Yesterday I tried to fly in a fixed wing with the stabilized mode. I had flown it well several times before. But unfortunately, yesterday, it has been suddenly disarmed during the climb out phase and crashed.
I checked the flight log by using the Flight Review but could not find the reason.
Could anyone help me to find its reson?


Fixed wing crash due to sudden disarm during climb out