an instance of 'xxx' is already running. Choose stop to terminate and launch a new instance

I"m trying to run a sample UI design on Xcode. When I run first time it was successful. And when I change the UI design and hit run it says ' an instance of 'xxx' is already running. Choose stop to terminate and launch a new instance. When i hit stop button it hangs forever and nothing is happening.

I"m using iPhone6s Simulator.

I'm looking for a solution (currently i'm doing: force to quit Xcode,simulator + then restart restart Xcode)to run the program without restarting Xcode.


I tried to clean+build the project but still the same. I've attached the screenshot, kindly have a look and give me a solution.

I have the same problem, but in regards to physical device. The process is running and I am unable to stop it/force quit it.

an instance of 'xxx' is already running. Choose stop to terminate and launch a new instance
 
 
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