Troubleshooting tips for iOS 13 and Xamarin.iOS

Updating to Xcode 11 stops the simulator from launching

After updating to Xcode 11 beta 1 every time a simulator is launched the following exception is thrown, and the simulator does not start. This happens with all simulators.


Foundation.ObjCException: NSInvalidArgumentException: -[SimDevice registerNotificationHandler:]: unrecognized selector sent to instance 0x7ffbf5d1e110


Until there is a fix, the following steps can be followed to re-install the old simulator framework to allow developers to continue to work:


These steps assume you have two Xcode applications:

  • – The beta version which does not work with simulators and Visual Studio for Mac.
  • – A stable version of Xcode 10. Yours might also be called

Change the command line examples below as appropriate for your configuration.

  1. Ensure that you have Xcode 11 selected via xcode-select:

    sudo xcode-select -s /Applications/

  2. Run, if needed, the setup tools for the first time.

    /Applications/ -runFirstLaunch

  3. Remove the following framework:

    sudo rm -Rf /Library/Developer/PrivateFrameworks/CoreSimulator.framework/Versions/*

  4. Switch back to the old Xcode version

    sudo xcode-select -s /Applications/

  5. Re-run the first launch tool for the OLD Xcode version you just selected

    /Applications/ -runFirstLaunch

After following these steps, you should be able to work with the iOS simulator again.