SECURITY WARNING: Never run commands you don't understand. Always review code before execution. Use at your own risk.
FixMyError.net
Dart New Added 10 September 2026

Dart: LateInitializationError: Field 'x' has not been initialized

late promises the compiler that a non nullable field will hold a value before anything reads it, and that promise was broken. Reading it during initState before the assignment, or on a code path where the assignment is conditional, throws at the point of the read rather than where the field was declared.

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

Quick fix
// Assign before anything can read it
late final ScrollController _controller;
@override
void initState() {
  super.initState();
  _controller = ScrollController();
}

// A late field with an initialiser is evaluated on first read, which is safer
late final client = ApiClient(baseUrl: config.baseUrl);

// If it might genuinely be absent, it is nullable, not late
Timer? _timer;
_timer?.cancel();

// Ask before reading, when the order is not under your control
if (_controllerInitialised) _controller.jumpTo(0);

// The build method can run before an async initialiser completes:
// hold the future and use FutureBuilder rather than a late field
late final Future<Config> _config = loadConfig();

How to diagnose Dart errors

Dart errors are dominated by null safety at runtime and version solving at build time. The null-check operator failure (! on a null) is Dart's equivalent of a NullPointerException and almost always means an assumption about initialisation order was wrong. Pub version solving failures are dependency-graph conflicts and are solved by reading the constraint that pub reports as unsatisfiable, not by deleting the lockfile.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

  1. Read the full pub get output. It names the two packages whose constraints conflict. Deleting pubspec.lock hides that information without fixing anything.
  2. Replace ! with a null check plus a meaningful error, or with late final where initialisation genuinely happens before first use. The crash location is where the assumption broke.
  3. Run flutter doctor -v before debugging any build failure. It catches missing Android SDK components and licence acceptance, which produce misleading Gradle errors.
  4. Use dart pub deps --style=tree to see the resolved graph and find which transitive dependency is pinning an old version.
  5. Clear derived state with flutter clean only after you have read the error. It resets the symptom and loses the evidence.

Tools worth reaching for

  • flutter doctor -v
  • dart pub deps
  • dart analyze
  • flutter run --verbose

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

dart.dev

Related Dart errors

See all 10 Dart errors →

Browse other categories

Something missing or wrong?

This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.