Fix: RenderBox was not laid out in Flutter
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.
Tag: flutter
122 posts · Page 9 of 13
Fix: A TextEditingController was used after being disposed in Flutter
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.
Fix: setState() or markNeedsBuild() called during build in Flutter
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.
How to Show Loading and Error States with AsyncValue in Flutter Riverpod
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.
How to Dispose Controllers in Flutter to Avoid Memory Leaks
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.
How to Handle Network Errors Gracefully in a Flutter App
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.
The Dart and Flutter MCP server: one command to give Claude Code your running Flutter app
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.
Dart records vs Freezed classes: which should you pick in 2026?
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.
Flutter vs React Native vs .NET MAUI: which should you pick for a new mobile project in 2026?
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 Drops the Initializer List for Private Fields
Dart 3.12 lets constructors initialize private fields directly with named parameters, killing one of the language's most persistent boilerplate patterns.