Flutter errorFlutter: “setState() called after dispose()”

What called setState too late, and the fix

1. 01

   A Future that finished after the user left

   “It is an error to call this method after the framework calls dispose.” Flutter, State.setState

   An await on an HTTP call or a database read takes a second; the user taps back; the call returns and runs setState. Check mounted right after each await that is followed by setState.

   Future<void> _load() async {
     final orders = await api.fetchOrders();
     if (!mounted) return;
     setState(() => _orders = orders);
   }

2. 02

   A Timer or periodic Timer still running

   “it is better practice to cancel whatever work might trigger the setState rather than merely checking for mounted before calling setState” Flutter, State.setState

   Timer.periodic keeps firing after the screen is gone. Keep the Timer in a field and cancel it in dispose().

   late final Timer _timer;
   
   @override
   void initState() {
     super.initState();
     _timer = Timer.periodic(const Duration(seconds: 1), (_) => setState(() => _seconds++));
   }
   
   @override
   void dispose() {
     _timer.cancel();
     super.dispose();
   }

3. 03

   A stream listener that was never cancelled

   “Subclasses should override this method to release any resources retained by this object” Flutter, State.dispose

   stream.listen in initState returns a StreamSubscription. Without cancel(), it calls setState on every event after the screen closes, and keeps the State in memory. Keep the subscription and cancel it in dispose(), or use a StreamBuilder, which handles it for you.

   late final StreamSubscription<User?> _sub;
   
   @override
   void initState() {
     super.initState();
     _sub = auth.authStateChanges().listen((user) => setState(() => _user = user));
   }
   
   @override
   void dispose() {
     _sub.cancel();
     super.dispose();
   }

4. 04

   A callback passed to another object

   “It is an error to call setState unless mounted is true.” Flutter, State.mounted

   An AnimationController, an animation or controller listener, or a callback stored by a service can outlive the screen. Remove listeners in dispose() with removeListener, and dispose every AnimationController and other controller you created. Code that runs from a global service should check mounted before touching the State.

Checked against the vendor’s docs on November 8, 2026: Flutter API: State.setState; Flutter API: State.mounted; Flutter API: State.dispose.

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