<p dir="auto"><strong>Note:</strong> I know this issue already exists in raised issue but I found it unresolved. Please don't close it as I included troubleshooting suggested by other threads too along with all outputs and snapshots. so its not a duplicate issue.</p>
<p dir="auto">I am using Windows 8.1 64bit<br>
having 7z and git installed on my system<br>
environment set properly</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/4740668/36932355-bfd62a08-1eed-11e8-9faa-2e7954c4db54.png"><img src="https://user-images.githubusercontent.com/4740668/36932355-bfd62a08-1eed-11e8-9faa-2e7954c4db54.png" alt="4" style="max-width: 100%;"></a></p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/4740668/36932370-f0b3a768-1eed-11e8-9fb1-169a55692704.png"><img src="https://user-images.githubusercontent.com/4740668/36932370-f0b3a768-1eed-11e8-9fb1-169a55692704.png" alt="5" style="max-width: 100%;"></a></p>
<p dir="auto">As per <a href="https://flutter.io/setup-windows/" rel="nofollow">getting started instructions to install flutter on windows</a>, I cloned flutter using the following command in <em>c:\android</em> directory and get a <em>c:\android\flutter</em> directory</p>
<p dir="auto"><code class="notranslate">git clone -b beta https://github.com/flutter/flutter.git</code></p>
<p dir="auto">set environment <code class="notranslate">c:\android\flutter\bin</code></p>
<p dir="auto">then I make a folder on the desktop called test and open PowerShell and CD to that folder and run following command</p>
<p dir="auto"><code class="notranslate">flutter doctor</code></p>
<p dir="auto">It says <code class="notranslate">Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...</code> repeatedly as following</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/4740668/36932408-71111e7c-1eee-11e8-9c4a-d4437e465db3.png"><img src="https://user-images.githubusercontent.com/4740668/36932408-71111e7c-1eee-11e8-9c4a-d4437e465db3.png" alt="2" style="max-width: 100%;"></a></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Checking Dart SDK version...
Downloading Dart SDK from Flutter engine ead227f118077d1f2b57842a32abaf105b573b8a...
Unzipping Dart SDK...
Updating flutter tool...
The system cannot find the path specified.
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

Waiting for 0 seconds, press CTRL+C to quit ...
The system cannot find the path specified.
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds..."><pre class="notranslate"><code class="notranslate">Checking Dart SDK version...
Downloading Dart SDK from Flutter engine ead227f118077d1f2b57842a32abaf105b573b8a...
Unzipping Dart SDK...
Updating flutter tool...
The system cannot find the path specified.
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

Waiting for 0 seconds, press CTRL+C to quit ...
The system cannot find the path specified.
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...
</code></pre></div>
<p dir="auto">I searched on google leading different issue pages and forums to resolve the issue. tried deleting cache directory and repeating <code class="notranslate">flutter doctor</code> command also didn't find any <em>$cachePath</em> folder anywhere in my system.</p>
<p dir="auto">tries a solution suggested on the issue <a href="https://github.com/flutter/flutter/issues/12666" data-hovercard-type="issue" data-hovercard-url="/flutter/flutter/issues/12666/hovercard">#12666</a> to <code class="notranslate">cd into flutter\packages\flutter_tools</code> and in there execute <code class="notranslate">..\..\bin\cache\dart-sdk\bin\pub.bat upgrade --verbosity=error --no-packages-dir</code></p>
<p dir="auto">but I guess it didn't work as there is nothing in my <em>C:\android\flutter\bin\cache\dart-sdk</em> directory and gives following errors</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/4740668/36932379-19c2af0a-1eee-11e8-8314-7f1e34cf9bac.png"><img src="https://user-images.githubusercontent.com/4740668/36932379-19c2af0a-1eee-11e8-8314-7f1e34cf9bac.png" alt="6" style="max-width: 100%;"></a></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="..\..\bin\cache\dart-sdk\bin\pub.bat : The term '..\..\bin\cache\dart-sdk\bin\pub.bat' is not recognized as the name
of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included,
verify that the path is correct and try again.
At line:1 char:1
+ ..\..\bin\cache\dart-sdk\bin\pub.bat upgrade --verbosity=error --no-p ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (..\..\bin\cache\dart-sdk\bin\pub.bat:String) [], CommandNotFoundExcepti
   on
    + FullyQualifiedErrorId : CommandNotFoundException"><pre class="notranslate"><code class="notranslate">..\..\bin\cache\dart-sdk\bin\pub.bat : The term '..\..\bin\cache\dart-sdk\bin\pub.bat' is not recognized as the name
of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included,
verify that the path is correct and try again.
At line:1 char:1
+ ..\..\bin\cache\dart-sdk\bin\pub.bat upgrade --verbosity=error --no-p ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (..\..\bin\cache\dart-sdk\bin\pub.bat:String) [], CommandNotFoundExcepti
   on
    + FullyQualifiedErrorId : CommandNotFoundException
</code></pre></div>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/4740668/36932382-2afa18a8-1eee-11e8-995c-dc62ccebd22a.png"><img src="https://user-images.githubusercontent.com/4740668/36932382-2afa18a8-1eee-11e8-995c-dc62ccebd22a.png" alt="3" style="max-width: 100%;"></a></p>
<p dir="auto">I tried to manually download dart-sdk and extract it inside <em>C:\android\flutter\bin\cache\dart-sdk</em> directory but it starts giving dependency error as following</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Updating flutter tool...
Incompatible version constraints on async:
- flutter_tools depends on version 2.0.4
- pub itself depends on version &gt;=1.8.0 &lt;2.0.0
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

Waiting for 0 seconds, press CTRL+C to quit ...
^CTerminate batch job (Y/N)? y"><pre class="notranslate"><code class="notranslate">Updating flutter tool...
Incompatible version constraints on async:
- flutter_tools depends on version 2.0.4
- pub itself depends on version &gt;=1.8.0 &lt;2.0.0
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

Waiting for 0 seconds, press CTRL+C to quit ...
^CTerminate batch job (Y/N)? y
</code></pre></div>
<p dir="auto">I tried uninstalling and re-installing everything again but nothing works.</p>
<p dir="auto">I noticed on executing <code class="notranslate">flutter doctor</code> command I do see a <strong>dart-sdk-windows-x64.zip</strong> file get downloaded inside <em>flutter\bin\cache</em> directory but it gets deletes itself soon after downloading and didn't get extracted.</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/4740668/36932388-3daca8bc-1eee-11e8-8895-f72158d96d88.png"><img src="https://user-images.githubusercontent.com/4740668/36932388-3daca8bc-1eee-11e8-8895-f72158d96d88.png" alt="1" style="max-width: 100%;"></a></p>
<p dir="auto"><strong>Results of <code class="notranslate">flutter run</code>, <code class="notranslate">flutter analyze</code> and <code class="notranslate">flutter doctor -v</code> are same</strong></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Updating flutter tool...
The system cannot find the path specified.
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

Waiting for 3 seconds, press CTRL+C to quit ...
Terminate batch job (Y/N)? y"><pre class="notranslate"><code class="notranslate">Updating flutter tool...
The system cannot find the path specified.
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

Waiting for 3 seconds, press CTRL+C to quit ...
Terminate batch job (Y/N)? y
</code></pre></div>
<p dir="auto"><strong>in case dart-sdk added manually following are the outputs of all the above commands i.e. <code class="notranslate">flutter run</code>, <code class="notranslate">flutter analyze</code> and <code class="notranslate">flutter doctor -v</code></strong></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Updating flutter tool...
Incompatible version constraints on async:
- flutter_tools depends on version 2.0.4
- pub itself depends on version &gt;=1.8.0 &lt;2.0.0
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

Waiting for 0 seconds, press CTRL+C to quit ...
^CTerminate batch job (Y/N)?"><pre class="notranslate"><code class="notranslate">Updating flutter tool...
Incompatible version constraints on async:
- flutter_tools depends on version 2.0.4
- pub itself depends on version &gt;=1.8.0 &lt;2.0.0
Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds...

Waiting for 0 seconds, press CTRL+C to quit ...
^CTerminate batch job (Y/N)?
</code></pre></div>
<p dir="auto">Do anyone find any prominent solution to this issue? If yes please share it.</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="flutter: ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
flutter: The following assertion was thrown building ExpansionPanelList:
flutter: 'package:flutter/src/material/mergeable_material.dart': Failed assertion: line 443 pos 18:
flutter: '_children[j] is MaterialGap': is not true.
flutter:
flutter: Either the assertion indicates an error in the framework itself, or we should provide substantially
flutter: more information in this error message to help you determine and fix the underlying cause.
flutter: In either case, please report this assertion by filing a bug on GitHub:
flutter:   https://github.com/flutter/flutter/issues/new
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #2      _MergeableMaterialState.didUpdateWidget (package:flutter/src/material/mergeable_material.dart)
flutter: #3      StatefulElement.update (package:flutter/src/widgets/framework.dart:3784:58)
flutter: #4      Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #5      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #6      Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #7      StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #8      Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #9      SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #10     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #11     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #12     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #13     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #14     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #15     StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #16     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #17     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #18     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #19     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #20     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #21     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #22     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #23     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #24     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #25     SliverMultiBoxAdaptorElement.updateChild (package:flutter/src/widgets/sliver.dart:744:36)
flutter: #26     SliverMultiBoxAdaptorElement.performRebuild (package:flutter/src/widgets/sliver.dart:702:34)
flutter: #27     SliverMultiBoxAdaptorElement.update (package:flutter/src/widgets/sliver.dart:671:7)
flutter: #28     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #29     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #30     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #31     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #32     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #33     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #34     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #35     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4379:32)
flutter: #36     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4769:17)
flutter: #37     _ViewportElement.update (package:flutter/src/widgets/viewport.dart:192:11)
flutter: #38     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #39     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #40     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #41     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #42     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #43     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #44     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #45     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #46     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #47     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #48     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #49     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #50     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #51     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #52     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #53     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #54     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #55     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #56     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #57     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #58     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #59     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #60     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #61     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #62     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #63     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #64     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #65     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #66     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #67     StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #68     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #69     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #70     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #71     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #72     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #73     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4379:32)
flutter: #74     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4769:17)
flutter: #75     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #76     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #77     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #78     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #79     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #80     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #81     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #82     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #83     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #84     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4379:32)
flutter: #85     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4769:17)
flutter: #86     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #87     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #88     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #89     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #90     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #91     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #92     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #93     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #94     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #95     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #96     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #97     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #98     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #99     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #100    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #101    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #102    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #103    StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #104    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #105    SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #106    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #107    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #108    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #109    StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #110    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #111    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #112    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #113    StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #114    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #115    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #116    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #117    ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #118    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #119    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #120    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #121    ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #122    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #123    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #124    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #125    StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #126    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #127    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #128    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #129    BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2242:33)
flutter: #130    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding&amp;WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:626:20)
flutter: #131    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
flutter: #132    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
flutter: #133    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
flutter: #134    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:842:5)
flutter: #135    _invoke (dart:ui/hooks.dart:120:13)
flutter: #136    _drawFrame (dart:ui/hooks.dart:109:3)
flutter: (elided 2 frames from class _AssertionError)
flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════"><pre class="notranslate"><code class="notranslate">flutter: ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
flutter: The following assertion was thrown building ExpansionPanelList:
flutter: 'package:flutter/src/material/mergeable_material.dart': Failed assertion: line 443 pos 18:
flutter: '_children[j] is MaterialGap': is not true.
flutter:
flutter: Either the assertion indicates an error in the framework itself, or we should provide substantially
flutter: more information in this error message to help you determine and fix the underlying cause.
flutter: In either case, please report this assertion by filing a bug on GitHub:
flutter:   https://github.com/flutter/flutter/issues/new
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #2      _MergeableMaterialState.didUpdateWidget (package:flutter/src/material/mergeable_material.dart)
flutter: #3      StatefulElement.update (package:flutter/src/widgets/framework.dart:3784:58)
flutter: #4      Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #5      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #6      Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #7      StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #8      Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #9      SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #10     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #11     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #12     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #13     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #14     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #15     StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #16     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #17     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #18     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #19     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #20     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #21     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #22     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #23     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #24     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #25     SliverMultiBoxAdaptorElement.updateChild (package:flutter/src/widgets/sliver.dart:744:36)
flutter: #26     SliverMultiBoxAdaptorElement.performRebuild (package:flutter/src/widgets/sliver.dart:702:34)
flutter: #27     SliverMultiBoxAdaptorElement.update (package:flutter/src/widgets/sliver.dart:671:7)
flutter: #28     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #29     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #30     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #31     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #32     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #33     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #34     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #35     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4379:32)
flutter: #36     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4769:17)
flutter: #37     _ViewportElement.update (package:flutter/src/widgets/viewport.dart:192:11)
flutter: #38     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #39     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #40     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #41     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #42     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #43     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #44     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #45     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #46     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #47     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #48     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #49     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #50     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #51     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #52     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #53     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #54     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #55     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #56     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #57     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #58     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #59     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #60     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #61     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #62     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #63     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #64     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #65     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #66     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #67     StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #68     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #69     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #70     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #71     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #72     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #73     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4379:32)
flutter: #74     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4769:17)
flutter: #75     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #76     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #77     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #78     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #79     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #80     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #81     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #82     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #83     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #84     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4379:32)
flutter: #85     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4769:17)
flutter: #86     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #87     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #88     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #89     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #90     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #91     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #92     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #93     ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #94     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #95     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #96     Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #97     StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #98     Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #99     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #100    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #101    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #102    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #103    StatelessElement.update (package:flutter/src/widgets/framework.dart:3702:5)
flutter: #104    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #105    SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4661:14)
flutter: #106    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #107    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #108    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #109    StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #110    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #111    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #112    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #113    StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #114    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #115    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #116    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #117    ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #118    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #119    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #120    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #121    ProxyElement.update (package:flutter/src/widgets/framework.dart:3909:5)
flutter: #122    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #123    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #124    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #125    StatefulElement.update (package:flutter/src/widgets/framework.dart:3799:5)
flutter: #126    Element.updateChild (package:flutter/src/widgets/framework.dart:2699:15)
flutter: #127    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3653:16)
flutter: #128    Element.rebuild (package:flutter/src/widgets/framework.dart:3495:5)
flutter: #129    BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2242:33)
flutter: #130    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding&amp;WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:626:20)
flutter: #131    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
flutter: #132    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
flutter: #133    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
flutter: #134    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:842:5)
flutter: #135    _invoke (dart:ui/hooks.dart:120:13)
flutter: #136    _drawFrame (dart:ui/hooks.dart:109:3)
flutter: (elided 2 frames from class _AssertionError)
flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════
</code></pre></div>