国内上传Dart包至pub.dev遇Connection closed错误（exit code 69）求助

身处中国，尝试将Dart包上传至pub.dev时，始终返回以下错误：

Connection closed before full header was received
pub finished with exit code 69

已尝试的无效解决方法 #

• 设置终端代理：

  $ export http_proxy=http://127.0.0.1:7890
  $ export https_proxy=$http_proxy
  
  $ curl google.com
  <HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
  <TITLE>301 Moved</TITLE></HEAD><BODY>
  <H1>301 Moved</H1>
  The document has moved
  <A HREF="http://www.google.com/">here</A>.
  </BODY></HTML>
  

• 编辑~/.bash_profile（已注释国内镜像配置）：

  # export PUB_HOSTED_URL=https://pub.flutter-io.cn
  # export FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn
  

  执行$ source ~/.bash_profile使配置生效。
• 尝试不同上传命令：

  $ flutter packages pub publish --server=https://pub.dartlang.org
  $ flutter pub publish --server=https://pub.dev
  
  ...
  # 返回错误
  Connection closed before full header was received
  pub finished with exit code 69
  

Flutter环境检测结果 #

$ flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.3.9, on macOS 12.6.1 21G217 darwin-x64, locale zh-Hans-CN)
[✓] Android toolchain - develop for Android devices (Android SDK version 33.0.1)
[✓] Xcode - develop for iOS and macOS (Xcode 14.2)
[✓] Chrome - develop for the web
[✓] Android Studio (version 4.2)
[✓] VS Code (version 1.75.1)
[✓] Proxy Configuration
[✓] Connected device (3 available)
[✓] HTTP Host Availability

内容的提问来源于stack exchange，提问作者张英姿