解决Flutter HTTP主机可用性问题及项目运行连接重置异常

问题描述 #

• 迁移至 Ubuntu 22.04 系统，已成功安装 Flutter（Channel main，3.4.0-19.0.pre.295）与 Android Studio（2021.2）
• 运行项目时抛出异常：

Exception in thread "main" java.net.SocketException: Connection reset

• 执行 flutter doctor 时，HTTP Host Availability 检查超时崩溃，日志如下：

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel main, 3.4.0-19.0.pre.295, on Ubuntu 22.04.1 LTS 5.15.0-47-generic, locale en_US.UTF-8)
Checking Android licenses is taking an unexpectedly long time...
[✓] Android toolchain - develop for Android devices (Android SDK version 33.0.0)
[✓] Chrome - develop for the web
[✓] Linux toolchain - develop for Linux desktop
[✓] Android Studio (version 2021.2)
[✓] VS Code
[✓] Connected device (3 available)
HTTP Host availability check is taking a long time...
[☠] HTTP Host Availability (the doctor check crashed)
    ✗ Due to an error, the doctor check did not complete. If the error message below is not helpful, please let us know about this issue at
      https://github.com/flutter/flutter/issues.
    ✗ Exception: HTTP Host Availability exceeded maximum allowed duration of 0:04:30.000000

! Doctor found issues in 1 category.

注：执行 flutter doctor 时已连接互联网

解决方法 #

• 检查网络代理设置
  关闭系统全局代理，或执行以下命令清除 Flutter 代理配置：

  flutter config --no-proxy
  

• 验证关键域名连通性
  测试 Flutter 依赖域名的连通性：

  ping storage.googleapis.com
  ping dl.google.com
  

  若无法连通，切换公共 DNS（如 8.8.8.8）：

  sudo nano /etc/resolv.conf
  # 修改或添加：nameserver 8.8.8.8
  

• 延长 Flutter Doctor 超时时间
  通过环境变量调整超时限制：

  export FLUTTER_DOCTOR_HTTP_TIMEOUT=300
  flutter doctor
  

• 重置 Flutter 环境
  清理缓存并重新获取依赖：

  flutter clean
  flutter pub get
  

  手动运行 Android 许可证检查：

  flutter doctor --android-licenses
  

• 切换至 Flutter 稳定通道
  当前使用的 main 通道为开发版，存在不稳定因素，切换至稳定通道：

  flutter channel stable
  flutter upgrade
  

内容的提问来源于stack exchange，提问作者user17893652