Key points: Flutter errors — this guide helps you identify the cause and remedy it as quickly as possible.
When building apps using Flutter, you come across a lot of the same errors again and again. I’ve distilled the top 10 problems I see on teams and side projects, why they happen, and clean fixes you can use immediately.
Why this guide helps
Brief, in-depth explanations with code examples to copy and paste plus references to the original sources. Pro tip: give the quick fixes a shot before adding the robust solution.
Common Causes
Fluter errors tend to fall into a few buckets:
- Async lifecycle mismatches (setState after dispose)
- Layout constraints and overflow (RenderFlex error)
- Dependency version conflicts (pub get)
- Null-safety and type issues
- Assumptions of wrong widget tree (use context)
Top 10 Errors (short list)
- setState() called after dispose
- RenderFlex overflowed
- LateInitializationError / null-safety errors
- NoSuchMethodError (wrong type)
- pub get fails — What are dependency conflicts
- Platform channel / native integration gone wrong
- hot reload is not picking up changes
- GestureDetector or InkWell not responding
- Image loading / memory issues
- Weighty & janky build method
Step-by-step Fix
Code samples with brief explanations of a few typical fixes will be presented below.
1) Fix: setState() called after dispose
Check for mounted before updating state, or if u really hate it cancel the async work in dispose.
class MyWidgetState extends State { bool _loading = false;
@override
void initState() {
super.initState();
_load();
}
Future _load() async {
setState(() => _loading = true);
await Future. delayed(Duration(seconds: 2));
if (! mounted) return; // ✅ make sure componentDidMount has to finish!
setState(() => _loading = false);
}
@override
void dispose() {
// cancel controllers/timers here, if necessary
super.dispose();
}
} Explanation: When we check whether is mounted，we will no permit update after dispose. Cancel all controllers and subscription in dispose().
2) Fix: RenderFlex overflowed
Use Flexible/Expanded or make your view scrollable.
Row(
children: [
Expanded(child: Text("I'm a long text that breaks as much into the available space")),
Icon(Icons.arrow_forward),
],
)Explanation: Expanded causes Flutter to distribute any available space and prevents overflow.
3) Fix: Pub dependency conflicts
Relax your constraints or force it using `dependency_overrides`.
# pubspec.yaml dependencies: http: ^1.1.0 some_package: ^2.0.0
if and only if you are sure:
dependency_overrides:
http: 1.1.0 Comment: prefer the resolution version by updating the dependent package over long-term forcing of overrides.
More quick fixes & checks
- Null-safety: add appropriate typing and named parameters as required by new syntax.
- Context errors: don't call Navigator.of(context) after an async delay -- check mounted first.
- Platform specific crashes: test on real devices, read native logs (adb logcat / Xcode console).
- Strange hot reload: do a full restart if state isn't syncing.
Frequently Asked Questions
1. Why is setState giving an error after the navigation?
and that's because the widget was disposed when you navigating. Go with checkIf mounted or stop task before navigate.
2. How can I prevent RenderFlex overflow in small devices?
Design responsive layouts — use Flexible, Expanded, media query or wrap with SingleChildScrollView.
3. When should I use dependency_overrides?
Only for the short term — to grease the wheels of building. Instead, focus on fixing upstream package compatibility rather than sending overrides to production.
Conclusion
These are the typical Flutter errors you’ll encounter time and again. Begin with the easy stopgaps (mounted, overflow widgets, pubspec) and progress to sturdy patterns: cancel async work, compact build methods, test on devices.
If you still can't see your way past one error, cut down the code which fails and test that in smaller pieces — very often this will reveal the actual problem.
Test the fixes now