Today while flying my screen went grey & froze.  Controler gave me an error message like "lost connection."  This hasn't happened before and i tried to remain calm but can't recall the exact message.  Soon i realized i could still fly the drone and I could see it so i landed.  I powered off and back on and recalibrated.  Flew again and it was fine.  This has be worried however- as you can imagine about all the what if's.  This could have been bad.  I'm asking the group for advice please.  I see the return to home button on the contoler and i assume that would have worked.  This is my second DJI drone and i've been flying for several years.  I just want to ask if this has happened to others and how best to be prepared.  I went through 5 batteries today and it happened on the third so significant time before after the incident with no trouble.   Thoughts and guidance please and thank you.  

Ive had the Go 4 app crash a couple of times when flying,  but a force quit and re launch of the app and all was fine.  But it is heart stopping.

Since the last firmware upgrade, I have had several Go 4 crashes on the Smart Controller. The range was minimal, and the controller was still connected, just the app crashed. If you are using the Goggles RE, then you will not see the crash on the transmitter screen and miss the opportunity to immediately restart Go4. You still maintain live view and camera control in the Goggles. This issue SEEMS to have resolved, although I have had to re-bind the drone. Yes, it is troubling, although I have become accustomed to the quickest method to restart the app. I would assume that if the signal is actually lost, RTH would be invoked...