Undefined name AdaptiveAutoRouter used as an annotation

I keep on getting this error (Android Studio).

lib/routes/router.dart:

import 'package:auto_route/auto_route.dart';
import 'package:salomon_routing_tutorial/home_page.dart';
...
@AdaptiveAutoRouter(
  replaceInRouteName: 'Page,Route',
...

pubspec.yaml:

name: salomon_routing_tutorial
description: Flutter Bottom Navigation with Nested Routing Tutorial.
publish_to: 'none'
version: 1.0.0+1
environment:
  sdk: ">=2.17.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.2
  auto_route: ^6.0.5
  salomon_bottom_bar: ^3.1.0

dev_dependencies:
  flutter_test:
    sdk: flutter

  flutter_lints: ^1.0.4
  auto_route_generator: ^6.0.3
  build_runner: ^2.1.2
  analyzer: ^5.10.0
flutter:
  uses-material-design: true

A typo should be out of the question, the name in question is copied from a working project. What could it be?

Try this..

1. Delete your router.dart and router.gr.dart (if created) file

2. Create a file app_router.dart and copy below code.

   import 'package:auto_route/auto_route.dart';
   import 'package:flutter/material.dart';       
   part 'app_router.gr.dart';
   
   @AutoRouterConfig(replaceInRouteName: 'Page,Route')
   class AppRouter extends _$AppRouter {
   
     @override      
     RouteType get defaultRouteType => const RouteType.adaptive(); //.cupertino, .adaptive ..etc 
   
    @override
    final List<AutoRoute> routes = [
     //routes here
    ];
   }
   

save and run build_runner