Crashed: com.apple.root.default-qos
I would double check all your permissions. In my case, starting with iOS10 you need permissions to save stuff to the user's camera roll. In my app, I was showing a default share sheet and whenever a user selected "save photo" the app crashed with one of these very not helpful error messages. I added
<key>NSPhotoLibraryAddUsageDescription</key> <string>Allow you to save charts and graphs from the app to your phone.</string>to my info.plist, clean & run. And everything the problem was solved.