Unable to determine simulator device to boot. - Xcode

Question

I just downloaded Xcode 6 & played with it a bit.

After switching back to previous version of Xcode and running in simulator, I keep getting this error.

Answer 1

There was a simple answer to this for me:

1. Open the simulator via Xcode -> Open Developer Tool -> iOS simulator (even if it can't launch, the app will be open).
2. With the simulator app open, go to Hardware -> Device -> Manage Devices.
3. Add any missing simulators with the plus button (all of mine were missing for some reason).

Answer 2

I think you have 2 simulator running in the dock. Please close another one simulator and run the project again. It might helpful for you.

Answer 3

My case wasn't about having two simulators open. It was just because having instruments open as well. Closing Instruments resolved the issue

Answer 4

I've faced same issue and solved by below steps:

1) Move xcode6-beta into application folder

2) Restart mac and open xcode6-beta from application folder.

Answer 5

I just fixed the exact same problem by removing the beta version and rebooting the computer.

Answer 6

Make sure you have only one iOS Simulator instance running in the Dock.