If you happen to have installed XCODE 7 and XCODE 8 say to support an old version of your app(s) and the new flame-resistant app better than the sun and the moon together. Occasionally XCODE 8 complains that it can’t find your simulators. All you see is the generic target.
The symptom is further validated by typing the following in the terminal:
Fret no more. This issue is caused because either the system has loaded the service used by the simulator associated to XCODE7 or because you recently opened it. And yes, likely you have closed it but the service still running even the front end app is closed. To fix it, type the following in the terminal:
launchctl remove com.apple.CoreSimulator.CoreSimulatorService || true
You won’t receive any output from the command you just executed, however, to validate that really worked, just retype the same command as in the console image above. You will see now the list of the simulators has you would have expected.