WebClient - The remote server returned an error: (403) Forbidden

问题

Opening a public page from browser works fine.

Downloading same page using WebClient throws - (403) Forbidden.

What is going on here ?

Here is quick copy/paste example (used on console app) to specific page on web:

try
{
    WebClient webClient = new WebClient();
    string content = webClient.DownloadString("http://he.wikisource.org/wiki/%D7%A9%D7%95%D7%9C%D7%97%D7%9F_%D7%A2%D7%A8%D7%95%D7%9A_%D7%90%D7%95%D7%A8%D7%97_%D7%97%D7%99%D7%99%D7%9D_%D7%90_%D7%90");
}
catch (Exception ex)
{
    throw;
}

回答1:

I've just tried it with Fiddler running to see the response and it returns the following notice with the status code.

Scripts should use an informative User-Agent string with contact information, or they may be IP-blocked without notice.

This works.

    WebClient webClient = new WebClient();
    webClient.Headers.Add("user-agent", "Only a test!");

    string content = webClient.DownloadString("http://he.wikisource.org/wiki/%D7%A9%D7%95%D7%9C%D7%97%D7%9F_%D7%A2%D7%A8%D7%95%D7%9A_%D7%90%D7%95%D7%A8%D7%97_%D7%97%D7%99%D7%99%D7%9D_%D7%90_%D7%90");

回答2:

Check if the server, you are trying to access is set up to use improved TLS protocol. Make sure to add this to Global.asax.cs

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

来源：https://stackoverflow.com/questions/2794260/webclient-the-remote-server-returned-an-error-403-forbidden