There's not much data on a 919 error - about all I can get is that it has something to do with a misconfigured internet connection. (Not on your phone - either on your carrier's gateway or on your router on wifi.) So the next time you get it, switch data modes. If you're on 3G/4G, try wifi. If you're on wifi, try your phone's data connection. Whichever way works, it's the other one that's misconfigured.