Bad state: Unable to generate package graph, no /.dart_tool/flutter_gen/pubspec.yaml` found

Question

When I am using auto_route package, I am getting this error when running build_runner:

Unhandled exception:
Bad state: Unable to generate package graph, no `/Users/myuser/AndroidStudioProjects/myproject/.dart_tool/flutter_gen/pubspec.yaml` found.
#0      _pubspecForPath (package:build_runner_core/src/package_graph/package_graph.dart:268:5)
#1      _parsePackageDependencies (package:build_runner_core/src/package_graph/package_graph.dart:242:21)
#2      PackageGraph.forPath (package:build_runner_core/src/package_graph/package_graph.dart:120:33)
<asynchronous suspension>
#3      main (file:///Users/myuser/.pub-cache/hosted/pub.dev/build_runner-2.4.8/bin/build_runner.dart:27:30)
<asynchronous suspension>

Here is my dev dependencies:

dev_dependencies:
  flutter_test:
    sdk: flutter

  flutter_lints: ^3.0.2
  build_runner: ^2.4.8
  json_serializable: ^6.7.1
  freezed: ^2.4.7
  auto_route_generator: ^8.0.0

Answer 1

Add this package to your dev_dependencies in pubspec.yaml:

dev_dependencies:
  flutter_test:
    sdk: flutter
  
  flutter_gen: ^version