Was doing a simple fly by video shot today and the app just stopped working when the drone was in mid flight. Good thing the controller is still in control of the drone.

Everything is updated including the latest firmware. Nothing was out of the ordinary pre effort checks are ok.

I think this is a common for Android users. First thing to do is to not panic. The 2 -3 times the app stopped on me the Home screen came up, I tapped the DJI Go 4 app icon and was immediately taken back to the flight screen with live video and and all of the current Spark readings. This took less than 5 seconds to regain the feed from the Spark using the smartphone tethered to the RC. Since I'm not making any money off of the Spark, it's just a hobby for me, I consider this more of an annoyance than anything else.

Sure I wish DJI could make the app more stable under Android and maybe eventually they will with the user's help. As a former software engineer, the best way to eliminate bugs is to be presented with data that causes an unexpected behavior. In this case, if you can replicate the app crash I would submit a support ticket and feedback response to make sure this info gets to the Android app group to correct.  

The phone was in fly-mode?