This has come up two days in a row now, and it has just started. I haven't changed any settings anywhere. It is annoying and inconvenient, and I don't receive my mail until I do this. I have an iPhone 6, iOS 10.0.2. My Apple ID is a gmail account. I use the native mail app on the iPhone. I also have an iPad mini which uses the native Apple mail app, and I use the gmail app on an iPad. All of these devices share the same apple ID. I access the gmail account via a Windows 10 computer as well. I have 2 step verification enabled on the gmail account. When I access the gmail account with the iPhone, a popup comes up saying the password is missing and I tap settings. I am taken to the settings and I see the spot to re-enter the password. Once I do that, it seems OK for the day, then the next morning it happens again. I have had this happen before sporadically, but two days in a row... I haven't changed any settings anywhere...what is the problem? I can't remember if, in the past, I have used an app specific password. Entering my gmail account password does work, but it seems to only work for 24 hours on the iPhone. The iPads are not having any problem.