The Flutter & Dart tracker

Flutter web 3.41 to 3.44 reports a ~625x line-height override when an Android WebView's textZoom is not 100. Upgrade to 3.47, or clear the override in MaterialApp.builder.

A reload only revalidates index.html, so an unhashed main.dart.js keeps coming from the browser cache. Send Cache-Control: no-cache for the Flutter build output, stamp a build id where you cannot set headers, and let the self-cleaning service worker retire pre-3.41 caches.

Your app imports material_ui but google_fonts 8.2.1 still returns the SDK TextTheme. Build the TextTheme yourself from GoogleFonts.roboto tear-offs until google_fonts migrates.

The release APK shipped without libapp.so. Flutter 3.44.0 to 3.44.4 could drop it: upgrade to 3.44.5 or later and split the combined subprojects block.

dart fix takes one target directory and it can be the repo root: the analyzer opens a context per nested pubspec.yaml and migrates every package in one pass. Here is the full flag surface, the four things that silently suppress fixes and make a dirty repo report Nothing to fix, why the exit code is useless in CI, and a case where a Flutter transform emits code that does not compile.

ImageIcon flattens a multi-color PNG into a silhouette because it always applies ColorFilter.mode(iconThemeColor, BlendMode.srcIn). Flutter 3.47 adds useOriginalColors to switch that off. Here is why passing color: null never worked, what useOriginalColors silently drops, and the hand-rolled replacement for older SDKs.

flutter attach has no --flavor option, so the resident compiler it spawns never defines FLUTTER_APP_FLAVOR and the appFlavor const collapses to null on the first hot restart. Three fixes: default-flavor in pubspec.yaml, flutter run --use-application-binary, and a platform channel that reads the flavor natively. Verified on Flutter 3.47.2 / Dart 3.13.2.

onChanged never fires because no edit happens, and on iOS the engine's deleteBackward returns without touching anything when the field is empty. Two approaches that actually work on every platform: a zero-width sentinel that guarantees an edit, and a single EditableText behind painted cells. Verified on Flutter 3.47.2 / Dart 3.13.2.

ref.watch subscribes and rebuilds, ref.read reads once and never rebuilds. Use watch in every build method and read only inside event callbacks. Here is the decision matrix, the source of both methods in flutter_riverpod 3.4.3, and the four silent failure modes: watch in a callback, read in a provider body, read on an autoDispose provider, and read used as an optimization.

A Key is the identity half of Widget.canUpdate, the one line of framework code that decides whether an Element and its State are reused or thrown away. Here is what that means in practice, the exact list edits that corrupt state without keys, which key type to reach for, and where the key has to sit to work.

A step-by-step migration off the deprecated dart:html, dart:js_util, and package:js onto package:web 1.1.1 and dart:js_interop: how to find every offending import with the dart2wasm compiler, what dart fix does and does not rename, the JSImmutableListWrapper and innerHTML traps, and how to verify with flutter build web --wasm.

The full migration off package:flutter/material.dart and package:flutter/cupertino.dart onto material_ui 1.1.1 and cupertino_ui 1.0.2: what dart fix --code=migrate_design_widgets rewrites, why third-party widgets start throwing ancestor-lookup errors, what MaterialUiCompatibilityBridge actually fixes, and how the flutter_localizations dependency changes.

Firebase Auth restores the Android session from a private SharedPreferences file with no network call, so a release-only sign-out is never broken persistence. It is a different google-services.json, a rejected token refresh, App Check, or your own catch block.

build_runner fails to compile because source_gen 3.1.0 or 4.0.0 calls an analyzer API removed in analyzer 8.4.0. Upgrade the generator that pins source_gen below 4.0.1.

A thread shares memory with every other thread in the process. A Dart isolate does not: it owns its heap, runs one event loop, and talks to other isolates only by messages. Here is what that means at the VM level, where isolate groups blur the line, and how it plays out in Flutter, FFI, and on the web.

Inside testWidgets the ambient clock from package:clock is already fake, but it starts at whatever wall time the test began. Pin it for a whole suite by overriding runTest on a custom AutomatedTestWidgetsFlutterBinding installed from flutter_test_config.dart. Verified on Flutter 3.44.2, clock 1.1.2, fake_async 1.3.3.

The JEP 472 warning on JDK 24+ is harmless and prints once. Fix it by matching your JDK to a Gradle version that supports it, not by pasting flags into gradle.properties.

getToken() runs before APNs hands iOS the device token. Poll getAPNSToken() until it returns non-null, then call getToken(). Check the Push Notifications capability if it never arrives.

Targeting Android SDK 35 puts your Flutter app in edge-to-edge mode, so the Scaffold body draws behind the navigation bar. Consume the insets with SafeArea and MediaQuery padding instead of opting out, because the opt-out is already dead on Android 16.

Gradle is compiling with a JRE. It is not searching your machine, it is using the exact JVM it was launched on. Point flutter config --jdk-dir at a real JDK, or clear org.gradle.java.home.

The 3.47.1 hotfix validates plugin class and package identifiers before they land in GeneratedPluginRegistrant. Here is the hole it closes, the regex that closes it, and the other 11 fixes in the release.

google_sign_in 7.0.0 made GoogleSignIn a singleton. Replace GoogleSignIn(scopes: ...) with GoogleSignIn.instance, await initialize() once, then call authenticate().

iOS 26 simulator runtimes are arm64-only, so a leftover EXCLUDED_ARCHS arm64 line builds an Intel-only Runner no simulator can execute. Drop the exclusion.

Flutter 3.47.0 stable flips desktop apps from Skia to Impeller without touching a line of your runner code. Here is what moves, how to opt out on each platform, and why that opt-out is temporary.

Pick by the return type of build(): T means Notifier, FutureOr<T> means AsyncNotifier, Stream<T> means StreamNotifier. Here is the decision matrix, the type hierarchy that explains why, and the == filtering and state-clobbering gotchas that bite each one. Verified against flutter_riverpod 3.4.2 on Flutter 3.44.2.

The SDK Manager is re-unpacking a corrupt archive it cached in .downloadIntermediates. Delete that folder and the half-extracted ndk/<version> directory, then re-run the build.

Play rejects the bundle because a 64-bit .so still has 4 KB ELF segments. Find the offending library, rebuild it with NDK r28+, and verify with zipalign -P 16.

iOS blocks the Dart VM from flipping memory pages to executable, so JIT dies at startup. Upgrade to Flutter 3.35.0 or later for iOS 26, 3.32.0 for iOS 18.4. There is no entitlement that fixes it.

Radio.groupValue and Radio.onChanged were deprecated after Flutter 3.32 and RadioGroup shipped in 3.35. A step-by-step migration for Radio, RadioListTile and CupertinoRadio, why dart fix cannot do it for you, and the generic type-inference trap that silently renders a migrated radio disabled. Verified on Flutter 3.44.2 stable.

Install the Android SDK Command-line Tools so the binaries land in <sdk>/cmdline-tools/latest/bin, point ANDROID_HOME at the SDK root, then re-run flutter doctor.

Wrap the subtree in Material(type: MaterialType.transparency) or put the screen in a Scaffold. MaterialApp alone does not provide a Material ancestor, which is why TextField and InkWell assert.

Attach a ScrollController to a ListView.builder, fire the next page when position.extentAfter drops below a prefetch threshold, and guard the fetch with isLoading, hasMore, and error flags. Full implementation plus the short-first-page trap.

Flutter 3.44.8 stable still ships no public multi-window API. Here is how to turn on the experimental windowing feature flag on the main channel, use RegularWindowController and WindowManager to open real top-level windows, and what to ship instead if you need stable today.

The keyboard shrinks your Scaffold body's max height, so a Column that just fit now overflows. Wrap the body in a scrollable instead of turning resizeToAvoidBottomInset off.

Read the second line of the error, not the first. It names the cause: a stale Podfile.lock snapshot, a deployment target that is too low, or two plugins pinning the same transitive pod.

That line is a wrapper, not the error. Re-run with flutter run --verbose or ./gradlew assembleDebug --stacktrace, read the real Gradle failure, then fix that.

The asset key is missing from the compiled bundle, not from your disk. Fix the pubspec indentation, add the trailing slash, match the key exactly, then full restart.

A complete guide to shipping a Flutter web app compiled to WebAssembly on Flutter 3.44: what the two emitted builds look like, why Firefox and Safari still get JavaScript because of the loader's wasmAllowList, migrating off dart:html for dart2wasm, the COOP/COEP headers that decide whether skwasm runs multi-threaded, and how to prove at runtime which build the browser actually loaded.

A step-by-step move from widget-local setState to a Riverpod 3.x Notifier: classify what actually leaves the widget, write the Notifier, convert to ConsumerWidget, and survive the == filtering, build() re-entry, and autoDispose defaults that bite setState refugees. Tested on Flutter 3.44, Dart 3.x, flutter_riverpod 3.3.2.

Install flutter_riverpod for almost every Flutter app. Use riverpod only for Dart-only code, and hooks_riverpod only if you already use flutter_hooks.

In Riverpod 3.0 every provider filters listener notifications with ==, not identity. A StreamProvider that re-emits the same mutable object stops rebuilding the UI after the first frame. Here is why it happens and three ways to fix it. Tested on flutter_riverpod 3.3.2, Flutter 3.44, Dart 3.x.

Riverpod 3.0 retries a failed provider up to 10 times by default. Pass a retry function that returns null on ProviderScope, ProviderContainer, or an individual provider to turn it off or bound it.

This error means the BuildContext you passed is above the Scaffold or ScaffoldMessenger, not below it. Wrap the caller in a Builder, extract it into its own widget, or use a GlobalKey.

This runtime error means a null reached a cast expecting a non-nullable type, almost always from JSON. Make the field nullable, or supply a default before the cast runs.

Wrap the same widget on both routes in a Hero with an identical tag and Flutter animates its position and size across the navigation. Full guide: images, flightShuttleBuilder, createRectTween, RectTween arcs, gesture transitions, and the tag collisions that break it. Tested on Flutter 3.44, Dart 3.12.

A stream keeps emitting after the user leaves the screen, its onData calls setState on a disposed State, and Flutter throws. Store the subscription, cancel it in dispose before super.dispose, and the callback can never fire on a dead widget. The full pattern for Flutter 3.44.

After an await, the widget may already be disposed, and calling setState throws. Guard the resume with if (!mounted) return; and, better, cancel the work that triggers it. The full pattern for Flutter 3.44.

A step-by-step upgrade from flutter_riverpod 2.x to 3.x: bump the packages, move StateProvider and friends to the legacy import, drop the AutoDispose and Family ref types, handle ProviderException wrapping and automatic retry, and fix the == notification filtering that silently drops StreamProvider events. Tested on Flutter 3.44, Dart 3.x, flutter_riverpod 3.3.2.

Flutter 3.44 exposes the device's rounded display corners through MediaQuery.displayCornerRadiiOf. Stop guessing a magic radius and clip your UI to the exact hardware curve on Android API 31+.

go_router and auto_route both sit on top of Navigator 2.0, so the real choice is declarative URL routing vs code-generated typed routes vs hand-rolling the Router API. A decision matrix with config for each, and when raw Navigator still wins.

For a long list, never use shrinkWrap. Use Expanded when the list is the only scrollable, and slivers (CustomScrollView) when it shares a scroll with other sections. Here is why, with a build-count benchmark.

Riverpod 3.0 wraps errors thrown while reading a provider in a ProviderException. Catch that type and read e.exception to get your original error back, or use AsyncValue.error which is unwrapped.

Dot shorthands went stable in Dart 3.12.2. Write .center or .new and let the compiler infer the type from context. Here is how they work across enums, static members, and constructors.

Move the color inside the decoration: use decoration: BoxDecoration(color: ...) instead of passing both color and decoration to the same Container.

This error means an Expanded or Flexible is not a direct child of a Row, Column, or Flex. Move it directly under the flex widget, or drop Expanded if the parent is not a flex.

The slivers list of a CustomScrollView only accepts slivers. Wrap box widgets in SliverToBoxAdapter, or swap ListView/Padding/Column for SliverList and SliverPadding.

In a Notifier, resolve dependencies before the await, then guard the state write with if (!ref.mounted) return. This is the Riverpod 3.0 replacement for the old onDispose mixin, and it stops UnmountedRefException when a provider is disposed mid-await. Tested on flutter_riverpod 3.x, Flutter 3.44, Dart 3.x.

Put a list and a grid in a single continuous scroll without nested scrollables. Use CustomScrollView with SliverList and SliverGrid, and skip the shrinkWrap trap that quietly kills performance.

Why a ListView in a Column throws 'Vertical viewport was given unbounded height', and the four fixes (Expanded, Flexible, shrinkWrap, SizedBox) with the performance trade-offs that decide which one you want.

This crash means you read a late field before anything assigned it. Initialize it synchronously in initState, or stop using late and model the async value as nullable state.

The ! operator hit a null at runtime. Replace it with ?. and ?? for a safe default, or guard with an explicit null check, instead of asserting a value that was not there.

Build a persistent shell with nested routes using ShellRoute and StatefulShellRoute, then wire up path-based deep links that rebuild the full page stack. Full config for Android and iOS, plus the gotchas that break the back stack.

Capture what you need from the context before the await, then guard the resume with if (context.mounted) return. Here is the full pattern, the lint that enforces it, and the edge cases it misses.

A step-by-step migration from an inline FutureBuilder widget to a Riverpod AsyncNotifier in a real Flutter app: move the async work out of build, expose it as a provider, render with .when() or switch pattern matching, and add refresh and mutation methods. Tested on Flutter 3.44, Dart 3.x, flutter_riverpod 3.3.2.

A version-pinned guide to moving a legacy Flutter 2.x app to a current Flutter 3.x release, with the sound null safety migration as the hard gate: why you need a two-hop path through Dart 2.19, what dart migrate does, and what breaks along the way.

A step-by-step migration from the provider package to Riverpod 3.x in a real Flutter app: ChangeNotifierProvider to Notifier, MultiProvider to ProviderScope, context.watch to ref.watch, ProxyProvider to ref.watch composition, plus the equality and lifecycle gotchas that bite. Tested on Flutter 3.27.1, Dart 3.11, provider 6.1.5, flutter_riverpod 3.3.1.

Use FutureBuilder or StreamBuilder for a self-contained, throwaway async widget. Reach for Riverpod AsyncValue once the result is shared, cached, or mutated. Here is the decision, the gotchas, and runnable code for both. Tested on Flutter 3.44 and flutter_riverpod 3.3.1.

This crash means a WidgetRef was used after its widget left the tree, usually in an async callback. Read what you need before the await, then guard with a mounted check.

This crash means you called context.of() after the widget left the tree, usually in an async callback or dispose(). Capture the value before the await, or in didChangeDependencies().

FutureBuilder re-runs your async work every time the parent rebuilds because you created the Future inside build. Hoist it into State.initState (or memoize it), and FutureBuilder will reuse the same Future. Here is the why, the repro, and every variant that bites.

Dart 3.12 adds an experimental primary constructors syntax that declares fields and a constructor in the class header, collapsing the classic three-line data class to one.

Pick Riverpod for most new Flutter apps in 2026. Choose Bloc for large teams that want an enforced event-driven structure, and keep Provider only for legacy code.

RenderBox was not laid out is almost always a secondary error. Find the first layout assertion above it, usually a scrollable given unbounded constraints, and fix that.

This crash means code touched a controller after dispose() ran. Guard async callbacks with a mounted check, and never dispose a controller you do not own.

This error means you mutated state while Flutter was building. Move the setState out of build, or defer it with addPostFrameCallback. Here is why it happens and the right fix.

Render loading, data, and error UI from a single AsyncValue in Riverpod 3. Use AsyncNotifier and AsyncValue.guard for mutations, .when() and switch pattern matching for the UI, keep previous data on refresh, and migrate the legacy StateNotifier pattern. Tested on flutter_riverpod 3.x, Flutter 3.44, Dart 3.x.

AnimationController, TextEditingController, and ScrollController hold resources that Dart's GC cannot reclaim until you dispose them. Here is the correct pattern, the ordering rules, and how to catch leaks before they ship.

A request can fail with no connectivity, a timeout, a DNS failure, a 500, or malformed JSON, and each needs a different response. Here is how to catch the right exceptions, classify them, retry safely, and show a UI a user can act on.

Dart 3.12 ships dart mcp-server, the official MCP bridge into the Dart and Flutter toolchain. Register it once in Claude Code, Cursor, or Codex CLI and your agent gets hot reload, pub.dev search, and live widget introspection without copy-pasting a DTD URI.

Pick Dart 3.12 records for ephemeral, locally-shaped data with no methods, and Freezed 3.x classes for named domain models that need copyWith, sealed unions, JSON serialization, or any behaviour.

For a greenfield mobile app in 2026, pick Flutter 3.44 when pixel-identical UI and animation budget matter, React Native 0.82 when your team already lives in TypeScript and you need a real browser sibling, and .NET MAUI 11 when iOS and Android are part of a wider .NET product and you need first-party Microsoft support.

Dart 3.12 lets constructors initialize private fields directly with named parameters, killing one of the language's most persistent boilerplate patterns.

Firebase shipped experimental Dart support for Cloud Functions on May 6, 2026. HTTPS and callable triggers, AOT-compiled cold starts, and the Firebase CLI handles compilation.

The fix in 30 seconds: set android.useAndroidX=true and android.enableJetifier=true in android/gradle.properties, then find any plugin still on the old support library and upgrade or replace it.

The fix in 30 seconds: set minSdkVersion to 21 (or higher) in android/app/build.gradle. background_fetch is built on Android's JobScheduler, which only exists from API 21.

The fix in 60 seconds: upgrade Flutter to 3.24.4 or later, raise the Podfile platform to iOS 13, wipe Pods plus DerivedData, then pod install. The error rarely lives in your Dart code.

The fix in 30 seconds: your response body is not the JSON you think it is. Print the raw bytes, decode with utf8.decode(response.bodyBytes), and never feed an HTML error page or a BOM-prefixed string to jsonDecode.

The fix in 30 seconds: read the 'because' chain in the error, find the one constraint that boxes pub in, and either widen it or add a dependency_overrides entry. Do not start with flutter clean.

The fix in 30 seconds: wrap the offending child in Expanded or Flexible. Then read the rest to learn why Row and Column do not clip, what unbounded constraints actually mean, and which fix is right for each layout.

Flutter 3.44 stable freezes Material and Cupertino inside the SDK and points new work at the material_ui and cupertino_ui packages on pub.dev. SwiftPM also becomes the default for iOS and macOS, finally retiring CocoaPods.

Step-by-step migration from GetX to Riverpod 3.x in a real Flutter app: GetxController to Notifier, .obs to derived providers, Get.find to ref.watch, Get.to to go_router, plus snackbars, theming, and tests. Tested on Flutter 3.27.1, Dart 3.11, flutter_riverpod 3.3.1.

Step-by-step guide to finding and fixing jank in Flutter 3.27 with DevTools: profile mode, the Performance overlay, the Frame Analysis tab, the CPU Profiler, raster vs UI thread, shader warm-up, and Impeller-specific gotchas. Tested on Flutter 3.27.1, Dart 3.11, DevTools 2.40.

The 2026 way to set an accent color in Flutter with Material 3: ColorScheme.fromSeed, the colorSchemeSeed shorthand, the seven DynamicSchemeVariant options, dark mode, dynamic_color on Android 12+, and harmonizing brand colors. Tested on Flutter 3.27.1 and Dart 3.11.

Call native Android (Kotlin) and iOS (Swift) code from a Flutter 3.x app without writing a plugin: MethodChannel, EventChannel, BasicMessageChannel, the StandardMessageCodec type table, threading rules, and the cases where a plugin still wins.

When async/await is not enough: spawn a Dart isolate to run CPU-bound work off the UI thread. Isolate.run, Flutter's compute, long-lived workers with SendPort/ReceivePort, what can cross the boundary, and the JS/web caveat. Tested on Dart 3.11 and Flutter 3.27.1.

Practical guide to running one Flutter project against multiple SDK versions in CI: a GitHub Actions matrix with subosito/flutter-action v2, FVM 3 .fvmrc as the source of truth, channel pinning, caching, and the gotchas that bite when the matrix grows past three versions.

Fluorite is an open-source 3D game engine that embeds Google Filament rendering inside Flutter widgets and lets you write game logic in Dart.

Droido 1.2.0 landed on Feb 8, 2026 as a debug-only network inspector for Flutter. The interesting part is not the UI. It is the packaging story: keep a modern inspector in debug builds while ensuring release builds remain clean, small, and unaffected.

biometric_signature 10.0.0 adds simplePrompt() and new BiometricError values. Here is how to handle the breaking change and future-proof your Flutter 3.x auth flows.

TrailBase is an open-source, single-executable backend built on Rust, SQLite, and Wasmtime. Version 0.23.7 ships UI fixes and improved error handling.

A pragmatic workflow for debugging Flutter iOS apps from Windows: offload the build to macOS in GitHub Actions, install the IPA on a real iPhone, and use flutter attach for hot reload and DevTools.

particles_flutter 2.0.2 adds particle shapes, rotation, boundary modes, and emitters. A quick tour of what changed and a tiny integration snippet for Flutter 3.x projects.

The leadingDistribution property in Flutter's TextHeightBehavior controls how extra leading is distributed above and below glyphs. Here is when it matters and how to fix text that looks vertically off.

TypeMonkey, a Flutter desktop typing app, shows why desktop projects need clean architecture from day one: sealed states, interface boundaries, and testable logic.

Dart 3.12 dev tags are landing fast. Here is how to read the version string, pin a dev SDK in CI, and triage failures so your Flutter 3.x migration is a small PR instead of a fire drill.

Flet lets you build Flutter UIs with Python logic. Here are the real trade-offs: latency from event chatter, ecosystem mismatch with Dart plugins, and split-brain debugging -- plus when it actually makes sense.

mobile_rag_engine brings on-device RAG to Flutter with a Rust core, ONNX embeddings, HNSW vector search, and SQLite storage. A practical look at the API, integration flow, and shipping constraints.

FlutterGuard CLI scans your Flutter 3.x build artifacts for leaked secrets, debug symbols, and metadata. A practical workflow for integrating it into CI and handling what it finds.

Flutter 3.38.6 bumped engine.version, and that matters for reproducible builds. Learn how to pin the SDK in CI, avoid engine drift, and diagnose 'what changed' when builds break with no code changes.

tp_router is a generator-driven Flutter router that eliminates manual route tables. Annotate your pages, run build_runner, and navigate with typed APIs instead of stringly-typed paths.

Fix Flutter `MissingPluginException` 'No implementation found for method getAll' on shared_preferences and similar plugins (package_info_plus, etc.) — ProGuard, plugin registration, minSdkVersion, hot restart fixes.

This Flutter error occurs when calling a method on a null object reference. Learn how to diagnose and fix the NoSuchMethod error using the call stack and breakpoints.

The most likely cause of this error is an update to Flutter (flutter upgrade) which led to some incompatibility with your existing code or your project's dependencies. The Theme.of(context).accentColor property has been deprecated since Flutter 1.17 and is entirely removed from the current version, thus the error you are seeing. What to use instead Or, if…

Fix the Flutter error 'Your project requires a newer version of the Kotlin Gradle plugin' by updating the ext.kotlin_version in your build.gradle file to the latest Kotlin release.