"JavaScript Debug Configuration" debug launch for Dart project results in pub error "Directory "lib" is not allowed."

I've discovered the issue come ups when I change my content root. If I start a new default project and run the default simple web app the program launches fine and only has 

/usr/lib/dart/bin/pub serve web --port=38059

displayed in Pub Serve.

As soon as I change the content root to point to my existing application the problem begins to arise with both the line above and

/usr/lib/dart/bin/pub serve lib --port=54943

Most likely your project violates Pub Package Layout Conventions. 

I guess you have some *.dart file in web folder that references another *.dart file from lib folder by relative path (this may be an import, export or part statement). This doesn't work in dart. Make sure that:

• for each main library file - all of its parts are withing the same root dir (for example all in lib or all in web)
• there are no references from files in lib folder to files that are outside of lib
• files outside of lib (e.g. in web) may reference files in lib only using URI like package:ProjectName/fileInLib.dart
• starting points are not allowed in lib folder: you shouldn't have *.html files and *.dart files with main() method there

When you fix all of these, you should not see 'pub serve lib' any more.

This was the problem.  Thanks.

Alexander,

What about files in the /packages folder referenced within /lib/main_app.dart of a sample Polymer Dart project as in:

@HtmlImport('main_app.html')
library proactive_healthcare.lib.main_app;

import 'dart:html';

import 'package:polymer_elements/paper_input.dart';
import 'package:polymer/polymer.dart';
import 'package:web_components/web_components.dart';

/// Uses [PaperInput]
@PolymerRegister('main-app')
class MainApp extends PolymerElement {
  @property
  String text;

  /// Constructor used to create instance of MainApp.
  MainApp.created() : super.created();

  @reflectable
  String reverseText(String text) {
    return text.split('').reversed.join('');
  }
}

Do the three import statements in the header go against the rule of the second bullet item? Thanks.

Let me clarify the 2nd bullet:

• there are no references from files in lib folder to files in the same Dart package that are outside of lib

References to other packages are allowed in any file.

Thanks for the clarification.