I have an Xamarin iOS project and developing in Visual Studio 2017 and have app icons in an asset. Since I've upgraded to XCode 9/iOS11 the app icons aren't included anymore and Application Uploader would throw a ton of errors at me about the missing icons. Before XCode 9 it worked though.
Xamarin describes upgrading issues to iOS 11 here and there but nothing much for Visual Studio 2017 - a key is missing in Info.plist they say. But what key?
It turns out the solution is a really simple one. Open iOS project in Visual Studio 2017, open Info.plist in editor, go to Visual Assets and make sure that App Icons source is pointing towards correct asset (with app icons).
It will generate this Info.plist key and value (value might differ, based on where your app icons are):
This value can be added manually, as well, if you know what to add.