Flutter Fix Lab
Understand Flutter error diagnostics by seeing the broken state reproduced under controlled conditions, followed by the verified correction, official rule, and complete standalone source code.
Offline Error & Fix Search Index
Locally matches error phrases, stack trace signatures, and Flutter APIs without persisting raw logs or sending telemetry.
A RenderFlex overflowed by pixels on the right with yellow/black hazard caution stripes.
Wrap unbounded children in Expanded or Flexible to pass bounded constraints along the main axis.
Vertical viewport was given unbounded height when nesting scrollable ListView directly inside Column.
Give scroll views bounded height using Expanded, SizedBox, or shrinkWrap with NeverScrollableScrollPhysics.
Incorrect use of ParentDataWidget when Positioned or Expanded is wrapped in an intermediary container.
ParentDataWidget subclasses must be direct children of their respective parent RenderObject (Stack or Flex).
setState() called after dispose() on defunct State when asynchronous callbacks fire after navigation.
Cancel owned timers/subscriptions in dispose() and check if (!mounted) return; before calling setState().
AnimatedSwitcher fails to animate when state changes, snapping instantly because children omit keys.
Assign distinct ValueKey<T> to child widgets so Flutter element reconciliation detects the identity change.