I am testing an iPhone app paired with its Watch app. Build is Success, then the iPhone simulator launches and the screen appears correctly, then nothing. The corresponding simulator for the watch screen doesn't show up. In the debug window, I get "[WC] WCSession counterpart app not installed". That problem didn't happen when I started the first tests, then it came in. Have restarted XCode many times and restarted my Mac as well. For the target, I select the iPhone part, and a scheme with an iPhone paired to a watch (S4, 44). I have also tested with three different codes coming from three different sources (tutorials) and get the same problem. On the iPhone simulator, scrolling down, I see my app. Pressing the Install button doesn't do anything. I suspect a problem either in my XCode either in my Mac.