title: Flutter The Function Color isn't defined or Undefined class Color
body: <p>Okay I don't even know what to write. Everything was working fine a few hours ago. Then I saw Flutter upgrade is available. So I tried to upgrade. That's when everything started to fall apart. Anyway, I used VPN to run terminal commands. I was successful. After that, every single flutter project I am opening is showing this error.
  I tried with other projects.</p>
  <p>I can run and build apk but these errors are there. <strong>Here is the output of the run command:</strong></p>
  <pre><code>Launching lib\main.dart on POCOPHONE F1 in debug mode...
  Running Gradle task 'assembleDebug'...
  √ Built build\app\outputs\apk\debug\app-debug.apk.
  Installing build\app\outputs\apk\app.apk...
  D/FlutterActivity(27090): Using the launch theme as normal theme.
  D/FlutterActivityAndFragmentDelegate(27090): Setting up FlutterEngine.
  D/FlutterActivityAndFragmentDelegate(27090): No preferred FlutterEngine was provided. Creating a new FlutterEngine for this FlutterFragment.
  D/FlutterActivityAndFragmentDelegate(27090): Attaching FlutterEngine to the Activity that owns this Fragment.
  D/FlutterView(27090): Attaching to a FlutterEngine: io.flutter.embedding.engine.FlutterEngine@4b90e47
  D/FlutterActivityAndFragmentDelegate(27090): Executing Dart entrypoint: main, and sending initial route: /
  Debug service listening on ws://127.0.0.1:51142/_qlZxn05Q8o=/ws
  Syncing files to device POCOPHONE F1...
  W/.covidtrackerb(27090): Long monitor contention with owner Answers Events Handler1 (27294) at int java.lang.String.indexOf(java.lang.String, java.lang.String, int)(String.java:1742) waiters=0 in io.fabric.sdk.android.services.common.AdvertisingInfo io.fabric.sdk.android.services.common.IdManager.getAdvertisingInfo() for 1.302s
  W/.covidtrackerb(27090): Long monitor contention with owner Answers Events Handler1 (27294) at int java.lang.String.indexOf(java.lang.String, java.lang.String, int)(String.java:1742) waiters=1 in io.fabric.sdk.android.services.common.AdvertisingInfo io.fabric.sdk.android.services.common.IdManager.getAdvertisingInfo() for 1.300s
  D/NetworkSecurityConfig(27090): No Network Security Config specified, using platform default
  E/FirebaseInstanceId(27090): binding to the service failed
  E/AccessibilityBridge(27090): VirtualView node must not be the root node.
  I/.covidtrackerb(27090): ProcessProfilingInfo new_methods=3224 is saved saved_to_disk=1 resolve_classes_delay=8000
  E/AccessibilityBridge(27090): VirtualView node must not be the root node.
  I/flutter (27090): ::Data connection is available.
  E/AccessibilityBridge(27090): VirtualView node must not be the root node.
  I/flutter (27090): Instance of 'Future&lt;Response&gt;'
  I/flutter (27090): Instance of 'Future&lt;Response&gt;'
  I/flutter (27090): size response :2
  I/flutter (27090): [Instance of 'Response', Instance of 'Response']
  I/flutter (27090): CovidBdState Instance of 'AllData'
  E/AccessibilityBridge(27090): VirtualView node must not be the root node.
  </code></pre>
  <p><strong>Here is Dart Analysis:</strong></p>
  <pre><code>error: Undefined name 'Brightness'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:45)
  error: The method 'Color' isn't defined for the class '_HomePageState'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:53)
  error: The method 'Color' isn't defined for the class '_HomePageState'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:58)
  error: The method 'Color' isn't defined for the class '_HomePageState'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:74)
  error: The method 'Color' isn't defined for the class '_HomePageState'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:104)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:106)
  error: The method 'Color' isn't defined for the class '_HomePageState'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:113)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:115)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:128)
  error: The method 'Color' isn't defined for the class '_HomePageState'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:136)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:213)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:260)
  error: The method 'Color' isn't defined for the class 'todo'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:409)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:419)
  error: The method 'Color' isn't defined for the class 'HeatMapTile'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:435)
  error: The method 'Color' isn't defined for the class 'HeatMapTile'. (undefined_method at [covidtrackerbd] lib\main_screen.dart:455)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:537)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\main_screen.dart:547)
  error: The method 'Color' isn't defined for the class 'LoadingScreen'. (undefined_method at [covidtrackerbd] lib\screens\loadingScreen.dart:15)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\screens\loadingScreen.dart:41)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\screens\loadingScreen.dart:52)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\loadingScreen.dart:65)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\doctors_report.dart:64)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\doctors_report.dart:68)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\doctors_report.dart:131)
  error: Undefined name 'TextDecoration'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\doctors_report.dart:547)
  error: Undefined name 'TextDecoration'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\doctors_report.dart:555)
  error: Undefined name 'Brightness'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\formSubmissionPage.dart:24)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\formSubmissionPage.dart:81)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\formSubmissionPage.dart:85)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\formSubmissionPage.dart:95)
  error: Undefined name 'TextDecoration'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\formSubmissionPage.dart:439)
  error: Undefined name 'TextDecoration'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\formSubmissionPage.dart:447)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\neighbours_report.dart:58)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\neighbours_report.dart:62)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\neighbours_report.dart:102)
  error: Undefined name 'TextDecoration'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\neighbours_report.dart:391)
  error: Undefined name 'TextDecoration'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\neighbours_report.dart:398)
  error: Undefined name 'Brightness'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\possible_affected.dart:30)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\possible_affected.dart:65)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\possible_affected.dart:85)
  error: Undefined name 'Brightness'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\recurringUpdate.dart:15)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\self_reporting_page.dart:74)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\self_reporting_page.dart:94)
  error: Undefined name 'Brightness'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\survey_page.dart:19)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\survey_page.dart:43)
  error: Undefined name 'FontWeight'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\Report\survey_page.dart:45)
  error: The method 'Color' isn't defined for the class '_SurveyPageState'. (undefined_method at [covidtrackerbd] lib\screens\tabs\Report\survey_page.dart:58)
  error: The method 'Color' isn't defined for the class '_SurveyPageState'. (undefined_method at [covidtrackerbd] lib\screens\tabs\Report\survey_page.dart:102)
  error: Undefined name 'Brightness'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\developerStory.dart:10)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\developerStory.dart:23)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\developerStory.dart:34)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\developerStory.dart:41)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\developerStory.dart:48)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:25)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:25)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:26)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:26)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:27)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:27)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:28)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:28)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:29)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:29)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:30)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:30)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:31)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:31)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:33)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:33)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:34)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:34)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:35)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:35)
  error: The function 'Color' isn't defined. (undefined_function at [covidtrackerbd] lib\screens\tabs\home\constants.dart:36)
  error: Undefined class 'Color'. (undefined_class at [covidtrackerbd] lib\screens\tabs\home\constants.dart:36)
  error: Undefined name 'Brightness'. (undefined_identifier at [covidtrackerbd] lib\screens\tabs\location.dart:34)
  error: Undefined name 'TextAlign'. (undefined_identifier at [covidtrackerbd] lib\screens\widgets\snackPage.dart:20)
  info: Unused import: 'dart:async'. (unused_import at [covidtrackerbd] lib\main.dart:2)
  info: Unused import: 'package:firebase_crashlytics/firebase_crashlytics.dart'. (unused_import at [covidtrackerbd] lib\main.dart:8)
  info: Name non-constant identifiers using lowerCamelCase. (non_constant_identifier_names at [covidtrackerbd] lib\main_screen.dart:312)
  info: Name types using UpperCamelCase. (camel_case_types at [covidtrackerbd] lib\main_screen.dart:395)
  info: This method overrides a method annotated as @mustCallSuper in 'State', but doesn't invoke the overridden method. (must_call_super at [covidtrackerbd] lib\screens\tabs\Report\doctors_report.dart:33)
  info: Unused import: 'package:covidtrackerbd/services/authentication.dart'. (unused_import at [covidtrackerbd] lib\screens\tabs\Report\possible_affected.dart:5)
  info: Unused import: 'formSubmissionPage.dart'. (unused_import at [covidtrackerbd] lib\screens\tabs\Report\possible_affected.dart:9)
  info: Unused import: 'package:covidtrackerbd/services/api.dart'. (unused_import at [covidtrackerbd] lib\screens\tabs\Report\self_reporting_page.dart:3)
  info: Unused import: 'package:covidtrackerbd/services/json.dart'. (unused_import at [covidtrackerbd] lib\screens\tabs\Report\self_reporting_page.dart:5)
  info: Unused import: 'package:flutter_html/flutter_html.dart'. (unused_import at [covidtrackerbd] lib\screens\tabs\Report\self_reporting_page.dart:8)
  info: Unused import: 'package:flutter/cupertino.dart'. (unused_import at [covidtrackerbd] lib\screens\tabs\home\constants.dart:23)
  info: This method overrides a method annotated as @mustCallSuper in 'AutomaticKeepAliveClientMixin', but doesn't invoke the overridden method. (must_call_super at [covidtrackerbd] lib\screens\tabs\location.dart:29)
  </code></pre>
  <p><strong>BTW My Imports are just fine.
  Output of Flutter Doctor:</strong></p>
  <pre><code>Microsoft Windows [Version 10.0.18363.720]
  (c) 2019 Microsoft Corporation. All rights reserved.
  
  C:\Users\Momshad\Documents\GitHub\COVID-Tracker-BD-master\COVID-Tracker-BD-master\App&gt;flutter doctor
  Doctor summary (to see all details, run flutter doctor -v):
  [√] Flutter (Channel stable, v1.12.13+hotfix.8, on Microsoft Windows [Version 10.0.18363.720], locale en-001)
  
  [√] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
  [√] Android Studio (version 3.6)
  [√] IntelliJ IDEA Community Edition (version 2019.3)
  [√] VS Code (version 1.43.1)
  [!] Connected device
      ! No devices available
  
  ! Doctor found issues in 1 category.
  
  C:\Users\Momshad\Documents\GitHub\COVID-Tracker-BD-master\COVID-Tracker-BD-master\App&gt;
  </code></pre>
  <p><strong>Output of Flutter Doctor -v:</strong></p>
  <pre><code>C:\Users\Momshad\Documents\GitHub\COVID-Tracker-BD-master\COVID-Tracker-BD-master\App&gt;flutter doctor -v
  [√] Flutter (Channel stable, v1.12.13+hotfix.8, on Microsoft Windows [Version 10.0.18363.720], locale en-001)
      • Flutter version 1.12.13+hotfix.8 at C:\src\flutter
      • Framework revision 0b8abb4724 (7 weeks ago), 2020-02-11 11:44:36 -0800
      • Engine revision e1e6ced81d
      • Dart version 2.7.0
  
  
  [√] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
      • Android SDK at C:\Users\Momshad\AppData\Local\Android\sdk
      • Android NDK location not configured (optional; useful for native profiling support)
      • Platform android-29, build-tools 29.0.2
      • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
      • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b04)
      • All Android licenses accepted.
  
  [√] Android Studio (version 3.6)
      • Android Studio at C:\Program Files\Android\Android Studio
      • Flutter plugin version 44.0.2
      • Dart plugin version 192.7761
      • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b04)
  
  [√] IntelliJ IDEA Community Edition (version 2019.3)
      • IntelliJ at C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.1.3
      • Flutter plugin version 44.0.3
      • Dart plugin version 193.6911.31
  
  [√] VS Code (version 1.43.1)
      • VS Code at C:\Users\Momshad\AppData\Local\Programs\Microsoft VS Code
      • Flutter extension version 3.8.1
  
  [√] Connected device (1 available)
      • POCOPHONE F1 • 9ea76ae • android-arm64 • Android 10 (API 29)
  
  • No issues found!
  </code></pre>
  <p><strong>Output of  Packages Get:</strong></p>
  <pre><code>C:\src\flutter\bin\flutter.bat --no-color packages get
  Running &quot;flutter pub get&quot; in App...                                 1.6s
  Process finished with exit code 0
  </code></pre>
  <p><strong>Output of Packages Upgrade:</strong></p>
  <pre><code>C:\src\flutter\bin\flutter.bat --no-color packages upgrade
  Running &quot;flutter pub upgrade&quot; in App...                            13.3s
  Process finished with exit code 0
  </code></pre>
  <p><strong>Things I tried:</strong></p>
  <ol>
  <li>Re-installed Flutter, Dart and Android Stuido (Path var checked)</li>
  <li>Tried with Intellij &amp; VS Code, Same result.</li>
  <li>Restarted Dart Analysis Server</li>
  <li>Tried Flutter Clean</li>
  <li>Deleted the whole project and went back to old commits to see if something was wrong with the code.</li>
  </ol>
  <p>UPDATE: Got some errors:</p>
  <pre><code>Launching lib\main.dart on POCOPHONE F1 in debug mode...
  
  Compiler message:
  lib/initialize.dart:2:8: Error: Not found: 'dart:html'
  import 'dart:html';
         ^
  /C:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/http-0.12.0+4/lib/src/browser_client.dart:6:8: Error: Not found: 'dart:html'
  import 'dart:html';
         ^
  /C:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/http-0.12.0+4/lib/src/browser_client.dart:34:18: Error: 'HttpRequest' isn't a type.
    final _xhrs = &lt;HttpRequest&gt;{};
                   ^^^^^^^^^^^
  /C:/src/flutter/packages/flutter/lib/src/painting/_network_image_web.dart:64:12: Error: Method not found: 'webOnlyInstantiateImageCodecFromUrl'.
      return ui.webOnlyInstantiateImageCodecFromUrl(resolved); // ignore: undefined_function
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  /C:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/http-0.12.0+4/lib/src/browser_client.dart:58:34: Error: 'Blob' isn't a type.
        var blob = xhr.response as Blob ?? Blob([]);
                                   ^^^^
  /C:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/http-0.12.0+4/lib/src/browser_client.dart:46:15: Error: The method 'HttpRequest' isn't defined for the class 'BrowserClient'.
   - 'BrowserClient' is from 'package:http/src/browser_client.dart' ('/C:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/http-0.12.0+4/lib/src/browser_client.dart').
  Try correcting the name to the name of an existing method, or defining a method named 'HttpRequest'.
      var xhr = HttpRequest();
                ^^^^^^^^^^^
  /C:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/http-0.12.0+4/lib/src/browser_client.dart:58:42: Error: The method 'Blob' isn't defined for the class 'BrowserClient'.
   - 'BrowserClient' is from 'package:http/src/browser_client.dart' ('/C:/src/flutter/.pub-cache/hosted/pub.flutter-io.cn/http-0.12.0+4/lib/src/browser_client.dart').
  </code></pre>