Failed to find or create execution context for description <IBCocoaTouchPlatformToolDescription: 0x7fa8bad9a6f0>

Question

Restarting the CoreSimulatorService solved the issue on my machine.

sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService

I had the same problem after I upgrade my Xcode to version 10.3.

I just restart my Mac and problem solved!

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Hope this would work with you too :)

Mine happened when updating to Xcode 10.3

X-code helper didn't get the permission to control the computer.

This is what i did to solve the problem

System Preference > Security&Privacy > privacy tab > accessibility

give permission for 'Xcode Helper'

Restart X-code and kill all simulators like @riik stated

sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService

This issue is with xcode update 10.3 and mixpannel is gives this as build error

Steps to fix.

Open terminal and paste this

sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService

Clean Xcode and build. Thats all

After having a google I found a similar question here and here, summary of the some of the answers in that question:

• Make sure you are running the latest version of Xcode and you dont have a beta installed.
• Close Xcode and then opened up Activity Monitor. Terminate any Ibtool processes running and restart Xcode.
• Delete any custom color pickers you have installed in for Xcode, close the Xcode and relaunch
• Try recreating any nibs you may have changed.

summary from the Xamarin Forums link:

Uninstall Xamarin studio, Xcode
Delete /Libraries/Developer and ~/Libraries/Developer folders
Reboot
Reinstall Xcode, Xamarin studio

If none of these work could you check in the Console.app for any errors when building.

Hope this helps.

I had my Xcode files on an external drive in User/Library/Developer/CoreSimulator. The issue was fixed upon doing the command sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService then moving these developer files back onto the mac.