Flutter: `setState() called after dispose()` error

Question

When the user leaves a screen before an HTTP request finishes, I get `setState() called after dispose()`. How do I fix it properly?

Accepted Answer

The widget was removed from the tree while your async work was still running, and then its callback tried to update the dead widget.

**Quick fix**: check `mounted` after every `await`:

```dart
Future<void> _load() async {
  final data = await api.fetchItems();
  if (!mounted) return;
  setState(() => _items = data);
}
```

**Better long-term**: move async state out of widgets into a state-management layer (Riverpod, Bloc, or a `ChangeNotifier`). Those handle lifecycle and cancellation for you, and make the logic testable.

Also cancel what you own in `dispose()`: `StreamSubscription.cancel()`, controllers' `dispose()`, timers.

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