10 Flutter Mistakes I Still See in Production Apps (and How to Fix Them) | HackerNoon

Flutter has evolved into one of the top hybrid app development frameworks, thanks to its fast UI development and easy learning curve. Thousands upon thousands of developers push Flutter apps to the App Store and Play Store every month. But with great power comes great responsibility.

After reviewing dozens of projects, I noticed recurring mistakes—some minor, others serious performance and scaling bottlenecks—that, if not addressed properly, can lead to major headaches in production apps.

Here are 10 of the most common Flutter mistakes I observed, why they happen, and how to fix them.

1. Overusing StatefulWidgets

The Mistake

Developers often wrap whole screens with a StatefulWidget even when only a small part of the screen needs state updates.

The Fix

Extract state to smaller components so only vital components are rebuilt.

class HomeScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          CounterWidget(), // Only this rebuilds
          Expanded(child: HeavyContentWidget()),
        ],
      ),
    );
  }
}

class CounterWidget extends StatefulWidget {
  @override
  _CounterWidgetState createState() => _CounterWidgetState();
}

class _CounterWidgetState extends State<CounterWidget> {
  int counter = 0;

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        Text('Counter: $counter'),
        IconButton(
          icon: Icon(Icons.add),
          onPressed: () => setState(() => counter++),
        ),
      ],
    );
  }
}

2. Ignoring App Lifecycle Events

The Mistake

Improper handling of app lifecycle changes can lead to token mismanagement, improper connection changes handling, and even loss of unsaved user data in some cases.

The Fix

Use WidgetsBindingObserver to listen to lifecycle changes and handle relevant app components.

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> with WidgetsBindingObserver {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    switch (state) {
      case AppLifecycleState.paused:
        saveUserProgress();
        break;
      case AppLifecycleState.resumed:
        refreshSession();
        break;
      default:
        break;
    }
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) => MaterialApp(home: HomeScreen());
}

3. Neglecting Error Handling for Async API Calls

The Mistake

Failed async API calls can throw exceptions or even crash the app if not taken care of properly.

The Fix

Wrap your async API calls with try/catch block and handle failures gracefully:

Future<void> fetchData() async {
  try {
    final data = await api.getData();
    setState(() => items = data);
  } catch (e, stack) {
    log('Fetch error: $e', stackTrace: stack);
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text('Failed to load data. Please try again.')),
    );
  }
}

4. Bloated Build Methods

The Mistake

Using just build() method to contain all of your widget code making it bulky and inefficient.

The Fix

Break down your build() method code into smaller components:

Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(title: Text('Dashboard')),
    body: Column(
      children: [
        UserGreeting(user: user),
        Expanded(child: ActivityFeed()),
        FooterNavigation(),
      ],
    ),
  );
}

5. Hardcoding Screen Sizes

The Mistake

Using fixed hardcoded widths/heights values that can break UI on tablets or foldable devices.

The Fix

Use responsive layouts using MediaQuery:

final width = MediaQuery.of(context).size.width;
return Container(
  width: width * 0.8,
  child: Text('Responsive Design'),
);

6. Over-fetching Data

The Mistake

Fetching the same API data again and again unnecessarily.

The Fix

Cache data and manage it globally instead of calling the API every time:

late Future<List<Post>> postsFuture;

@override
void initState() {
  super.initState();
  postsFuture = api.fetchPosts();
}

FutureBuilder(
  future: postsFuture,
  builder: (context, snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return CircularProgressIndicator();
    } else if (snapshot.hasError) {
      return Text('Error: ${snapshot.error}');
    } else {
      return PostList(posts: snapshot.data!);
    }
  },
);

7. Ignoring Null Safety Edge Cases

The Mistake

Using ! operator everywhere without understanding the risks that come with it.

The Fix

Always use null-aware operators to avoid null data errors:

final username = user?.name ?? 'Guest';
if (user?.email != null) {
  sendEmail(user!.email!);
}

8. Blocking the Main Thread

The Mistake

Running heavy tasks (e.g., JSON parsing, encryption, loading DB) on the main thread that jams or janks the UI.

The Fix

Use isolates or async functions to avoid main thread blockage:

Future<int> processData(int value) async {
  return compute(_heavyTask, value);
}

int _heavyTask(int input) {
  // Heavy computation
  return input * 42;
}

9. Skipping Performance Profiling

The Mistake

App deployment without analyzing UI janks or widget rebuild counts that consume extra resources.

The Fix

• Use flutter run --profile and Flutter DevTools.
• Add const where possible.
• Track rebuilds:

10. Poor Internationalization (i18n) Practices

The Mistake

Hardcoding strings into Text() widgets and ignoring localizations.

The Fix

Use flutter_localizations or easy_localization to localize your app the proper way.

Using easy_localization

1. Add the package into your pubspec.yaml file:

dependencies:
  easy_localization: latest_version

2. Wrap your app with EasyLocalization

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await EasyLocalization.ensureInitialized();

  runApp(
    EasyLocalization(
      supportedLocales: [Locale('en'), Locale('es')],
      path: 'assets/translations', // JSON files here
      fallbackLocale: Locale('en'),
      child: MyApp(),
    ),
  );
}

3. Add translation as JSON files at

   assets/translations/en.json

{ "welcome": "Welcome to our app" }

and at assets/translations/es.json

{ "welcome": "Bienvenido a nuestra aplicación" }

4. Use translations in Text() widgets

Text('welcome'.tr());

Now adding new language support is just one JSON file away.

Final Thoughts

Flutter enables fast cross-platform app development and delivery, but speed can become a headache if not managed properly. Overusing StatefulWidget, hardcoding layouts, skipping lifecycle management, or ignoring i18n may not seem critical in the MVP phase, but they will create problems as your app scales.