当尝试运行flutter build web时，我得到"build web"当前不受支持。我以前遇到过错误，我被Dart 2.5.0-dev.4.0.flutter-be66176534卡住，需要2.5.0或更高版本，现在这个问题已经解决，但我无法构建我的项目。

flutter doctor -v
[√] Flutter (Channel stable, v1.9.1+hotfix.2, on Microsoft Windows [Version 10.0.18932.1000], locale en-GB)
    • Flutter version 1.9.1+hotfix.2 at C:\src\flutter
    • Framework revision 2d2a1ffec9 (8 days ago), 2019-09-06 18:39:49 -0700
    • Engine revision b863200c37
    • Dart version 2.5.0

[√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at C:\Users\germa\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)
    • All Android licenses accepted.

[!] Android Studio (version 3.4)
    • Android Studio at C:\Program Files\Android\Android Studio
    X Flutter plugin not installed; this adds Flutter specific functionality.
    • Dart plugin version 183.6270
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)

[√] VS Code (version 1.38.1)
    • VS Code at C:\Users\germa\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.4.1

我试过了

• 重装镖
• 重装Flutter
• 重新安装Visual Studio代码
• 复制文件内容到一个新的web项目（同样的错误）

我找不到任何有关此问题的原因以及如何在线解决的信息
我可以做些什么来解决这个错误？