The named parameter 'child' isn't defined. in Center() constructor

Question

I ran flutter upgrade today, and now I am getting an error that says-

[dart] The named parameter 'child' isn't defined.

The project is newly created and the default code is untouched, but it still has the same Error:

Answer 1

In my case it happens when I name the widget with the same name of a flutter component, like so:

class OutlineButton extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return OutlineButton(
      child: Text('+R\$ 5'),
      onPressed: () {},
      borderSide: BorderSide(color: Colors.grey),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(30.0),
      ),
    );
  }
}

You need to change the name of the created component with a different name, for example:

class CustomOutlineButton extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return OutlineButton(
      child: Text('+R\$ 5'),
      onPressed: () {},
      borderSide: BorderSide(color: Colors.grey),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(30.0),
      ),
    );
  }
}

Answer 2

Clean the project cache by running

flutter clean cache

Then invalidate caches / restart Android Studio or VS Code.

Answer 3

Try Restarting your Analysis Dart Server.

1. At the bottom of Android Studio click on the Dart Analysis tab
2. Click on the Restart icon.