DJI GO 4 shuts down during flight on my Samsung Galaxy S7 nearly every time.  I read through the forum where someone from DJI said to update the app from the DJI site instead of google play and this is still happening.  This is the 4th day since purchasing the drone.  Everything on my phone is up to date and I'm not having problems with any other apps.   

I had the same thing happen on my Iphone SE.  Once it started doing it, it would do it every time.  I would start a flight and BAM it was gone.  Restart the app...BAM it would shut down.  I deleted the app and reinstalled (not while flying!) and the behaviour stopped for now.  I recently read that if you "clear the cache" it will stop this.

I had it for awhile. Had to delete and reinstall the go app 3 times before it fixed the problem.
But that was an update or 2 ago and I now use Crystalsky.
Good thing is that even when the app crashes you still have control over the AC through the RC.

formatting the SD card on the SPARK chased the issue out of my Note 5 .  Also while you do a new apk install, dont forget to delete the previous DJI folders 'before you commence with the new installation

This was happening before I had an SD card in the Spark for 2 days.  First thing I did was format the SD card when I installed it.  Luckily I do have the controller, but they are sold without one so it's not a good thing to have happening.  I have cleared the cache in the app a couple of times.  I'll try deleting and reinstalling the app.

Mine shuts down on the Moto G5+. Hasn't happened since the new update though.