XcodeServer only one simulated device may be used at a time error

Question

I setup a bot to build the project then test on all the simulators. This has been working, but today the integration had 28 errors. Each said the same thing (but for each simulator device name):

Xcode cannot launch apps on the simulated device “Resizable iPad”, as it is currently running an app on “iPhone 5s”. Only one simulated device may be used at a time...

After manually running the bot I received no warnings. What could cause this? (I enjoy the success streak)

Answer 1

I only had one project running and had the same issue. Control Quit out of xcode and start it back up.

Answer 2

I had this same problem. I had multiple projects open and a different one still had

'Running appName on deviceName' displayed

Currently open projects can be accessed from the Window section on the toolbar on top. Pressing the Stop button (or the command from the Product Menu) on any projects that were still 'running' freed that particular device for other projects.

Alternatively, Rebooting Xcode works as it closes all projects.

See: https://stackoverflow.com/a/22267017/5172836

Answer 3

I encountered the same error today with the simulator. The only way i've find is to reboot Xcode. After that the error disappeared and the application launch corectely in the simulator. I don't know how the error has been originally produce, but Xcode is not a reliability model, so...