iphone 6 unexpected shutdown after ios 11.3 update Why ?

Yesterday I upgraded my iphone 6 OS to 11.3 so far I experience restart problem 3 times. While I am using my iphone it hanged and restart automatically. Why is this happening? How to fix this issue. Kindly guide.

Justinfzr5000,

Will it turn on? See this:

If your iPhone, iPad, or iPod touch won‘t turn on or is frozen

Good luck.

My iphone 6 restart due to facebook messenger. While using messenger when I swipe the finger in right direction my phone would be struck and restart. After upgrading my messenger to version 161 my problem is solved.

I have exactly the same problem..