As the service worker seems to be the "official" one I assume it can't be used like this in combination with functions. https://github.com/facebook/create-react-app/issues/2237#issuecomment-302693219 The Service worker will just return the app instead of the function itself. Only option is ejecting and extend `navigateFallbackWhitelist` option. I didn't test this with this package, but with a bare CRA app and functions which should be basically the same.