“Application windows are expected to have a root view controller at the end of application launch” error when running a project with Xcode 7, iOS 9

From your error message: Application windows are expected to have a root view controller at the end of application launch How old is this “old” project? If it’s more than a few years, do you still have: [window addSubview:viewController.view]; You should instead replace it with: [window setRootViewController:viewController];