flutter - android - http.get never returns in release mode

Question

I am writing a flutter app for android and ios. To log in, the app uses the http package (version 0.12.2) : http.Response response = await http.get(url);. In iOS, everything works fine. In Android, the debug mode works also fine, however, if I build the apk and install the app from this release apk, the async method http.get never returns. I use Android 9 on a OnePlus 3 (OxygenOS 9.0.6).

I am very new to flutter and can't figure this out. A similar issue is open in github but concerns flutter for web.

Here is a minimal code to reproduce. To test it, you should build the apk (Build > Flutter > Build apk)), copy and paste the apk in your phone files, install the app from the apk, press the button PRESS ME, done will never be displayed.

• main.dart

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Test flutter'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  String _status = "Press the button";

  void _test() async {
    String url = "http://dummy.restapiexample.com/api/v1/employees";

    // Send HTTP request to the server
    http.Response response = await http.get(
        url
    );

    setState(() {
      _status = "done";
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            // Test button
            RaisedButton(
                onPressed: _test,
                child: Text(
                  "PRESS ME",
                ),
              ),
            Text(
              '$_status',
            ),
          ],
        ),
      ),
    );
  }
}

• pubspec.yaml

name: flutter_test_app
description: Test app for reproducing minimal example

publish_to: 'none' # Remove this line if you wish to publish to pub.dev

version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  http: ^0.12.2

  cupertino_icons: ^0.1.3

dev_dependencies:
  flutter_test:
    sdk: flutter

flutter:
  uses-material-design: true

Solution

Hi you need to add networking permission to AndroidManifest.xml check this official documentation on flutter networking https://flutter.dev/docs/development/data-and-backend/networking

it is located in android/src/main/AndroidManifest.xml

<manifest xmlns:android...>
 ...
 <uses-permission android:name="android.permission.INTERNET" />
 <application ...
</manifest>