While I am try to run an app in the iOS 10 simulator using
Even I was getting the same error. Issue in my case was I was working on xcode 7.3 and its simulator was open, later on I closed xcode 7 and opened xcode 8 and tried running app and got the above error.
I guess its happening because of both the simulator were open, it got solved when I closed my older simulator. Seem to be some problem while xcode 8 was trying to establish connection with simulator.