在centos环境asp.net core出现The SSL connection could not be established异常。
如下：

用4种解决方式：

1 修改代码解决

  var httpClientHandler = new HttpClientHandler
    {
        ServerCertificateCustomValidationCallback = (message, certificate2, arg3, arg4) => true
    };
   HttpClient client = new HttpClient(httpClientHandler)

2 修改centos中asp.net core项目守护进程的配置文件

在environment节点下 设置

 DOTNET_SYSTEM_NET_HTTP_USESOCKETSHTTPHANDLER=0

3 程序运行时增加DOTNET_SYSTEM_NET_HTTP_USESOCKETSHTTPHANDLER=0
如：

DOTNET_SYSTEM_NET_HTTP_USESOCKETSHTTPHANDLER=0 dotnet Web.dll

**4 修改project.runtimeconfig.json文件

"runtimeOptions": {
  "configProperties": {
      "System.Net.Http.UseSocketsHttpHandler": false
  }
}