I was having trouble updating apps today. It would start and then tell me that the update failed, with an option to retry the update. After choosing to retry, it would work that time (on the second try).
Not sure if related to your issue...
It seems to me that there are a lot of App Store download issues as of late. Is this all just Apple's servers being complete **** or iOS 10-related?
Have had no issues downloading any app updates since iOS 10, maybe it's your Internet connection or something on your device? Apple's system status page doesn't indicate an issue either.