I was getting this error as well. (The run destination iPhone 12 Pro Max is not valid...) What resolved it was going into the Simulator setup window and deleting the paired watches from all the iOS simulators I was not using (such as iPhone 12 Pro Max).

Using onAppear did not work for me. I split the difference to get it to work for me, using    init() {       UITabBar.appearance().barTintColor = UIColor(Color(colorExtraLight)) // custom color.    } Also, with backgroundColor it appeared to be about 50% opaque, but barTintColor appeared solid. xcode 12.4/iOS 14.0

This does work, however... It seems to have a side effect of making a segmented picker inside the nav view unresponsive. (Oddly, a Toggle control does still work.) Bug or feature I'm not sure. I've tried the onTapGesture at different levels and also tried onDisappear, none of which resolved the issue. xcode 12.4/iOS 14.1

Thanks OOPer! Turns out all I needed was to add the onChange you suggested - needing both the onAppear and onChange. So the BackgroundView looks like this: swift struct BackgroundView: View { var status: String = "0" @State private var isAnimating: Bool = false var body: some View { ZStack { Group { Image(systemName: "\(status).circle.fill") .resizable() .scaledToFit() .frame(width: 220) .foregroundColor(.red) } .scaleEffect(isAnimating ? 1.0 : 0, anchor: .top) } .animation(Animation.easeOut(duration: 0.4), value: isAnimating) .onAppear(perform: { print("appear: \(status)") isAnimating = true }) .onChange(of: status) { _ in print("change: \(status)") isAnimating = false withAnimation(Animation.easeOut(duration: 0.4)) { isAnimating = true } } } }