I am seeing this error '_elements.contains(element)': is not true.for the past two days in my flutter project, this was working absolutely fine since the beginning. I am sorry to say this but I have no clue regarding this error but i think i am missing something which is causing this error. Also, when I hot reload the same page the layout is populated, but throws the exceptions.
Intermittently this was also showing Duplicate GlobalKeys() detected, but this wasn't the case in the beginning.
Please can someone help me if they stumbled upon these errors before. I couldn't really write an example to reproduce the same problem. Many thanks.
I have given the error details as follows:
Performing hot reload...
I/flutter (22248): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY
╞═══════════════════════════════════════════════════════════
I/flutter (22248): The following assertion was thrown building
TickerMode(mode: disabled):
I/flutter (22248): 'package:flutter/src/widgets/framework.dart': Failed
assertion: line 1766 pos 12:
I/flutter (22248): '_elements.contains(element)': is not true.
I/flutter (22248):
I/flutter (22248): Either the assertion indicates an error in the framework
itself, or we should provide substantially
I/flutter (22248): more information in this error message to help you
determine and fix the underlying cause.
I/flutter (22248): In either case, please report this assertion by filing a
bug on GitHub:
I/flutter (22248): https://github.com/flutter/flutter/issues/new
I/flutter (22248):
I/flutter (22248): When the exception was thrown, this was the stack:
I/flutter (22248): #2 _InactiveElements.remove
(package:flutter/src/widgets/framework.dart:1766:12)
I/flutter (22248): #3 Element._retakeInactiveElement
(package:flutter/src/widgets/framework.dart:2850:29)
I/flutter (22248): #4 Element.inflateWidget
(package:flutter/src/widgets/framework.dart:2873:32)
I/flutter (22248): #5 Element.updateChild
(package:flutter/src/widgets/framework.dart:2688:12)
I/flutter (22248): #6 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #7 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #8 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #9 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #10 RenderObjectElement.updateChildren
(package:flutter/src/widgets/framework.dart:4262:32)
I/flutter (22248): #11 _TheatreElement.update
(package:flutter/src/widgets/overlay.dart:508:17)
I/flutter (22248): #12 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #13 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #14 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #15 StatefulElement.update
(package:flutter/src/widgets/framework.dart:3682:5)
I/flutter (22248): #16 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #17 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #18 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #19 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #20 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #21 SingleChildRenderObjectElement.update
(package:flutter/src/widgets/framework.dart:4535:14)
I/flutter (22248): #22 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #23 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #24 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #25 StatefulElement.update
(package:flutter/src/widgets/framework.dart:3682:5)
I/flutter (22248): #26 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #27 SingleChildRenderObjectElement.update
(package:flutter/src/widgets/framework.dart:4535:14)
I/flutter (22248): #28 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #29 SingleChildRenderObjectElement.update
(package:flutter/src/widgets/framework.dart:4535:14)
I/flutter (22248): #30 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #31 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #32 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #33 StatefulElement.update
(package:flutter/src/widgets/framework.dart:3682:5)
I/flutter (22248): #34 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #35 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #36 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #37 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #38 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #39 SingleChildRenderObjectElement.update
(package:flutter/src/widgets/framework.dart:4535:14)
I/flutter (22248): #40 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #41 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #42 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #43 StatelessElement.update
(package:flutter/src/widgets/framework.dart:3607:5)
I/flutter (22248): #44 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #45 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #46 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #47 StatelessElement.update
(package:flutter/src/widgets/framework.dart:3607:5)
I/flutter (22248): #48 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #49 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #50 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #51 StatelessElement.update
(package:flutter/src/widgets/framework.dart:3607:5)
I/flutter (22248): #52 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #53 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #54 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #55 StatelessElement.update
(package:flutter/src/widgets/framework.dart:3607:5)
I/flutter (22248): #56 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #57 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #58 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #59 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #60 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #61 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #62 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #63 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #64 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #65 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #66 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #67 StatefulElement.update
(package:flutter/src/widgets/framework.dart:3682:5)
I/flutter (22248): #68 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #69 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #70 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #71 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #72 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #73 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #74 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #75 StatefulElement.update
(package:flutter/src/widgets/framework.dart:3682:5)
I/flutter (22248): #76 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #77 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #78 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #79 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #80 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #81 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #82 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #83 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #84 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #85 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #86 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #87 StatelessElement.update
(package:flutter/src/widgets/framework.dart:3607:5)
I/flutter (22248): #88 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #89 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #90 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #91 StatefulElement.update
(package:flutter/src/widgets/framework.dart:3682:5)
I/flutter (22248): #92 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #93 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #94 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #95 ProxyElement.update
(package:flutter/src/widgets/framework.dart:3792:5)
I/flutter (22248): #96 Element.updateChild
(package:flutter/src/widgets/framework.dart:2677:15)
I/flutter (22248): #97 ComponentElement.performRebuild
(package:flutter/src/widgets/framework.dart:3557:16)
I/flutter (22248): #98 Element.rebuild
(package:flutter/src/widgets/framework.dart:3446:5)
I/flutter (22248): #99 BuildOwner.buildScope
(package:flutter/src/widgets/framework.dart:2246:33)
I/flutter (22248): #100
BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&Renderer
Binding&WidgetsBinding.drawFrame
(package:flutter/src/widgets/binding.dart:580:20)
I/flutter (22248): #101
BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&Renderer
Binding._handlePersistentFrameCallback
(package:flutter/src/rendering/binding.dart:200:5)
I/flutter (22248): #102
BindingBase&SchedulerBinding._invokeFrameCallback
(package:flutter/src/scheduler/binding.dart:713:15)
I/flutter (22248): #103 BindingBase&SchedulerBinding.handleDrawFrame
(package:flutter/src/scheduler/binding.dart:649:9)
I/flutter (22248): #104
BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&Renderer
Binding.scheduleWarmUpFrame.<anonymous closure>
(package:flutter/src/rendering/binding.dart:286:20)
I/flutter (22248): #106 _Timer._runTimers (dart:isolate-
patch/dart:isolate/timer_impl.dart:367)
I/flutter (22248): #107 _Timer._handleMessage (dart:isolate-
patch/dart:isolate/timer_impl.dart:401)
I/flutter (22248): #108 _RawReceivePortImpl._handleMessage
(dart:isolate-patch/dart:isolate/isolate_patch.dart:163)
I/flutter (22248): (elided 3 frames from class _AssertionError and
package dart:async-patch)
I/flutter (22248):
══════════════════════════════════════════════════════════════════════════
══════════════════════════
Reloaded 0 of 492 libraries in 823ms.
I have included a sample example of what i am trying to do in my application.
main.dart
import 'package:flutter/rendering.dart';
import 'package:flutter/material.dart';
import 'package:untitled3/secondwidget.dart';
void main() {
runApp(
new Example(),
);
}
class Example extends StatefulWidget {
@override
_ExampleState createState() => new _ExampleState();
}
class _ExampleState extends State<Example> {
int noOfBranches;
@override
void initState() {
super.initState();
getCount();
}
void getCount() {
print('list builder count is ${noOfBranches}');
}
@override
Widget build(BuildContext context) {
setState(() {
noOfBranches = 2;
});
return new MaterialApp(
home: new Scaffold(
body: new ListView.builder(
itemCount: noOfBranches,
itemBuilder: (BuildContext context, int index) {
return new Card(
child: new FlatButton(
onPressed: (() {
Navigator.push(
context,
new MaterialPageRoute(
builder: (_) => new SecondWidget()));
}),
child: new Text('Next Widget')),
);
}),
),
);
}
}
secondwidget.dart
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
class SecondWidget extends StatefulWidget {
@override
_SecondWidgetState createState() => new _SecondWidgetState();
}
class _SecondWidgetState extends State<SecondWidget> {
@override
Widget build(BuildContext context) {
return new Container(
child: new Text('Second Widget'),
);
}
}
I don't see the error in my application if setState() declare as given in the example main.dart file inside the
@override
Widget build(BuildContext context) {
setState(() {
noOfBranches = 2;
});
.....
}
but I only see this error if I declare the setState() inside the getCount() function.
I am not so sure why this is the case.
I am actually stuck on this error for two days and any help would be greatly appreciated.
Many Thanks, Mahi
