I encountered a similar error after migrating from one mac to another.
In my case, I reinstalled simulator and after that everything works fine.
Here is the solution:
sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService
sudo rm -rf ~/Library/*/CoreSimulator
go to Window->Devices menu in Xcode then add the wanted simulators by taping the "+" button in the lower left corner of the window. (post)