Unhandled Exception: MissingPluginException(No implementation found for method init on channel plugins.flutter.io/google_sign_in code example

Example 1: unhandled exception: missingpluginexception(no implementation found for method launch on channel plugins.flutter.io/url_launcher)

If you are using hot restart or hot reload, it won't do the trick. Since Flutter has to inject plugin dependencies into the platform-specific parts of your app, hot restart/hot reload is not enough to trigger the injection. Check this issue for more.

Close the app and execute flutter run command.

Example 2: unhandled Exception: MissingPluginException(No implementation found for method Firebase#initializeCore on channel plugins.flutter.io/firebase_core)

Make sure your google-services.json file is copied into the correct folder