Problem

I was running React Native on iOS and got the error:

error Failed to launch the app on simulator, An error was encountered processing the command (domain=com.apple.CoreSimulator.SimError, code=405):
Unable to lookup in current state: Shutdown

Solution

Delete Xcode cache by going to:  > About This Mac > Storage > Manage... > Developer > Project Build Data and Indexes > Delete...

Rerun React Native and open the Simulator device:

npx react-native run-ios