为什么我会收到无法从 Web 应用程序而不是控制台应用程序连接到远程服务器的异常？

Question

I have a asmx web service running on a test server that has anonymous access enabled.

When I add the web reference to a console application and call a simple Hello World method like so:

PivotService.PivotService p = new PivotService.PivotService();
String s = p.SayHello();

When I do exactly the same thing in the page load of a web application I get a System.Net.WebException: {"Unable to connect to the remote server"} .

The inner exception is {"No connection could be made because the target machine actively refused it 127.0.0.1:8888"} , errorCode 10061.

Why would this work from a console app and not a web app?

Answer 1

It could be due to differences in the proxy settings between applications. Check out the MSDN documentation around the Default Proxy element in config file.

Answer 2

I too was in a similar situation while using HttpClient class from System.Net.Http namespace. I was trying to make a network call which goes through the company proxy server.

While this HttpClient call was able to successfully resolve the IP of the dns when called from a console app in visual studio the dns resolution failed when the call was made from a Web API. And it turned out that I had to have this entry in the web.config of the web api app.

<system.net>
    <defaultProxy />
</system.net>

Credit to Mark 909's answer for pointing me in right direction. Please see Default Proxy for additional information.

c# httpclient webapi

Answer 3

首先从控制台删除 web 引用运行你的 web 服务并复制 URL 到你的解决方案资源管理器并添加 web 引用（排除旧的）>高级>添加 web 引用添加粘贴 URL 然后添加你的 web 引用名称然后重建你的解决方案它工作正常为我

Answer 4

As @R Kiran Kumar suggests, I had to also add the proxy values:

<system.net>
    <defaultProxy>
      <proxy usesystemdefault="False"
             proxyaddress="Specify Your Proxy Address: Specify Port Number"
             // Example, "http://192.168.0.10:1234"
bypassonlocal="False"/>
    </defaultProxy>
  </system.net>

Answer 5

Use this line :

ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;

System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;

Just above the httpclient object creation