While working with older version of Dart code, getting an error in whole project

Question

The language version must be >=2.12.0. Try removing the language version override and migrating the code.

Looking for the solution for the above error.Illegal_language_version_override

//@dart=2.9
import 'dart:io';

import 'package:firebase_core/firebase_core.dart';

Error-
Illegal_language_version_override

Answer 1

Download Flutter and Dart with the required versions for your codebase, and update the path in system environment; this will resolve the mentioned issues.