Better BoxDecoration directionality error message

@nt4f04uNd

Disclaimer - this issue was picked for an entertaining-new-contributors educational project inside Yandex mobile schools. Please contact @nt4f04uNd that you are willing to work on it.

Running this code sample

import 'package:flutter/material.dart';

void main() {
  runApp(Container(
    decoration: BoxDecoration(
      border: Border.all(),
      borderRadius: BorderRadiusDirectional.all(Radius.circular(1.0)),
    ),
  ));
}

Gives this as output

════════ Exception caught by rendering library ═════════════════════════════════
The following assertion was thrown during paint():
'package:flutter/src/painting/border_radius.dart': Failed assertion: line 727 pos 12: 'direction != null': is not true.
2

Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=2_bug.md

The relevant error-causing widget was
Container Container:file:///C:/dev/projects/issues/lib/main.dart:10:12
When the exception was thrown, this was the stack
#2      BorderRadiusDirectional.resolve
package:flutter/…/painting/border_radius.dart:727
#3      _BoxDecorationPainter.paint
package:flutter/…/painting/box_decoration.dart:488
#4      RenderDecoratedBox.paint
package:flutter/…/rendering/proxy_box.dart:2162
#5      RenderObject._paintWithContext
package:flutter/…/rendering/object.dart:2409
#6      PaintingContext.paintChild
package:flutter/…/rendering/object.dart:189
#7      RenderView.paint
package:flutter/…/rendering/view.dart:209
#8      RenderObject._paintWithContext
package:flutter/…/rendering/object.dart:2409
#9      PaintingContext._repaintCompositedChild
package:flutter/…/rendering/object.dart:141
#10     PaintingContext.repaintCompositedChild
package:flutter/…/rendering/object.dart:100
#11     PipelineOwner.flushPaint
package:flutter/…/rendering/object.dart:979
#12     RendererBinding.drawFrame
package:flutter/…/rendering/binding.dart:455
#13     WidgetsBinding.drawFrame
package:flutter/…/widgets/binding.dart:883
#14     RendererBinding._handlePersistentFrameCallback
package:flutter/…/rendering/binding.dart:319
#15     SchedulerBinding._invokeFrameCallback
package:flutter/…/scheduler/binding.dart:1143
#16     SchedulerBinding.handleDrawFrame
package:flutter/…/scheduler/binding.dart:1080
#17     SchedulerBinding.scheduleWarmUpFrame.<anonymous closure>
package:flutter/…/scheduler/binding.dart:863
(elided 13 frames from class _AssertionError, class _RawReceivePortImpl, class _Timer, dart:async, and dart:async-patch)
The following RenderObject was being processed when the exception was fired: RenderDecoratedBox#ef365
RenderObject: RenderDecoratedBox#ef365
    parentData: <none>
    constraints: BoxConstraints(w=392.7, h=759.3)
    size: Size(392.7, 759.3)
    decoration: BoxDecoration
        border: Border.all(BorderSide(Color(0xff000000), 1.0, BorderStyle.solid))
        borderRadius: BorderRadiusDirectional.circular(1.0)
    configuration: ImageConfiguration(bundle: PlatformAssetBundle#6a1dc(), devicePixelRatio: 1.0, platform: android)
    child: RenderPadding#0d2c7 NEEDS-PAINT
        parentData: <none> (can use size)
        constraints: BoxConstraints(w=392.7, h=759.3)
        size: Size(392.7, 759.3)
        padding: EdgeInsets.all(1.0)
        child: RenderLimitedBox#7356c NEEDS-PAINT
            parentData: offset=Offset(1.0, 1.0) (can use size)
            constraints: BoxConstraints(w=390.7, h=757.3)
            size: Size(390.7, 757.3)
            maxWidth: 0.0
            maxHeight: 0.0
            child: RenderConstrainedBox#fdce1 NEEDS-PAINT
                parentData: <none> (can use size)
                constraints: BoxConstraints(w=390.7, h=757.3)
                size: Size(390.7, 757.3)
                additionalConstraints: BoxConstraints(biggest)
════════════════════════════════════════════════════════════════════════════════

It would be nice if that would be catched and rethrown with a better error message instructing what I have to do to fix that - similar to the assertion here

flutter/packages/flutter/lib/src/widgets/debug.dart

Lines 270 to 296 in 5575bf3

    
           bool debugCheckHasDirectionality(BuildContext context, { String? why, String? hint, String? alternative }) { 
        
             assert(() { 
        
               if (context.widget is! Directionality && context.getElementForInheritedWidgetOfExactType<Directionality>() == null) { 
        
                 why = why == null ? '' : ' $why'; 
        
                 throw FlutterError.fromParts(<DiagnosticsNode>[ 
        
                   ErrorSummary('No Directionality widget found.'), 
        
                   ErrorDescription('${context.widget.runtimeType} widgets require a Directionality widget ancestor$why.\n'), 
        
                   if (hint != null) 
        
                     ErrorHint(hint), 
        
                   context.describeWidget('The specific widget that could not find a Directionality ancestor was'), 
        
                   context.describeOwnershipChain('The ownership chain for the affected widget is'), 
        
                   ErrorHint( 
        
                     'Typically, the Directionality widget is introduced by the MaterialApp ' 
        
                     'or WidgetsApp widget at the top of your application widget tree. It ' 
        
                     'determines the ambient reading direction and is used, for example, to ' 
        
                     'determine how to lay out text, how to interpret "start" and "end" ' 
        
                     'values, and to resolve EdgeInsetsDirectional, ' 
        
                     'AlignmentDirectional, and other *Directional objects.', 
        
                   ), 
        
                   if (alternative != null) 
        
                     ErrorHint(alternative), 
        
                 ]); 
        
               } 
        
               return true; 
        
             }()); 
        
             return true; 
        
           }

@nt4f04uNd

@nt4f04uNd

On latest master, I see the same error log as you posted:


======== Exception caught by rendering library =====================================================
The following assertion was thrown during paint():
'package:flutter/src/painting/border_radius.dart': Failed assertion: line 727 pos 12: 'direction != null': is not true.


Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=2_bug.md

On latest stable though, it seems to be a bit better ?


======== Exception caught by rendering library =====================================================
The following _CastError was thrown during paint():
type 'BorderRadiusDirectional' is not a subtype of type 'BorderRadius?' in type cast

The relevant error-causing widget was: 
  Container file:///Users/dhs/Documents/NCFlutter/bug_test/lib/main.dart:4:10
When the exception was thrown, this was the stack: 
#0      _BoxDecorationPainter.paint (package:flutter/src/painting/box_decoration.dart:488:46)
#1      RenderDecoratedBox.paint (package:flutter/src/rendering/proxy_box.dart:2143:17)
#2      RenderObject._paintWithContext (package:flutter/src/rendering/object.dart:2317:7)
#3      PaintingContext.paintChild (package:flutter/src/rendering/object.dart:187:13)
#4      RenderView.paint (package:flutter/src/rendering/view.dart:200:15)

type 'BorderRadiusDirectional' is not a subtype of type 'BorderRadius?' in type cast which seems to give an indication what's wrong with the implementation and hence the error.

It is a fixed crash, see #88039. On stable it wouldn't resolve even if you wrapped the container with the Directionality.

Add detailed error message for BorderRadiusDirectional (#171805)

Add detailed error message for BorderRadiusDirectional (flutter#171805)

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

Add detailed error message for BorderRadiusDirectional (flutter#171805)

Add detailed error message for BorderRadiusDirectional (#171805)

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Better BoxDecoration directionality error message #88644

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	bool debugCheckHasDirectionality(BuildContext context, { String? why, String? hint, String? alternative }) {
	assert(() {
	if (context.widget is! Directionality && context.getElementForInheritedWidgetOfExactType<Directionality>() == null) {
	why = why == null ? '' : ' $why';
	throw FlutterError.fromParts(<DiagnosticsNode>[
	ErrorSummary('No Directionality widget found.'),
	ErrorDescription('${context.widget.runtimeType} widgets require a Directionality widget ancestor$why.\n'),
	if (hint != null)
	ErrorHint(hint),
	context.describeWidget('The specific widget that could not find a Directionality ancestor was'),
	context.describeOwnershipChain('The ownership chain for the affected widget is'),
	ErrorHint(
	'Typically, the Directionality widget is introduced by the MaterialApp '
	'or WidgetsApp widget at the top of your application widget tree. It '
	'determines the ambient reading direction and is used, for example, to '
	'determine how to lay out text, how to interpret "start" and "end" '
	'values, and to resolve EdgeInsetsDirectional, '
	'AlignmentDirectional, and other *Directional objects.',
	),
	if (alternative != null)
	ErrorHint(alternative),
	]);
	}
	return true;
	}());
	return true;
	}

Better BoxDecoration directionality error message #88644

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darshankawar commented on Aug 23, 2021

nt4f04uNd commented on Aug 23, 2021

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github-actions commented on Jul 24, 2025

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