Why I get 411 Length required error?

问题

This is how I call a service with .NET:

var requestedURL = "https://accounts.google.com/o/oauth2/token?code=" + code + "&client_id=" + client_id + "&client_secret=" + client_secret + "&redirect_uri=" + redirect_uri + "&grant_type=authorization_code";
HttpWebRequest authRequest = (HttpWebRequest)WebRequest.Create(requestedURL);
authRequest.ContentType = "application/x-www-form-urlencoded";
authRequest.Method = "POST";
WebResponse authResponseTwitter = authRequest.GetResponse();

but when this method is invoked, I get:

Exception Details: System.Net.WebException: The remote server returned an error: (411) Length Required.

what should I do?

回答1:

When you're using HttpWebRequest and POST method, you have to set a content (or a body if you prefer) via the RequestStream. But, according to your code, using authRequest.Method = "GET" should be enough.

In case you're wondering about POST format, here's what you have to do :

ASCIIEncoding encoder = new ASCIIEncoding();
byte[] data = encoder.GetBytes(serializedObject); // a json object, or xml, whatever...

HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
request.Method = "POST";
request.ContentType = "application/json";
request.ContentLength = data.Length;
request.Expect = "application/json";

request.GetRequestStream().Write(data, 0, data.Length);

HttpWebResponse response = request.GetResponse() as HttpWebResponse;

回答2:

you need to add Content-Length: 0 in your request header.

a very descriptive example of how to test is given here

回答3:

When you make a POST HttpWebRequest, you must specify the length of the data you are sending, something like:

string data = "something you need to send"
byte[] postBytes = Encoding.ASCII.GetBytes(data);
request.ContentLength = postBytes.Length;

if you are not sending any data, just set it to 0, that means you just have to add to your code this line:

request.ContentLength = 0;

Usually, if you are not sending any data, chosing the GET method instead is wiser, as you can see in the HTTP RFC

回答4:

var requestedURL = "https://accounts.google.com/o/oauth2/token?code=" + code + "&client_id=" + client_id + "&client_secret=" + client_secret + "&redirect_uri=" + redirect_uri + "&grant_type=authorization_code";
HttpWebRequest authRequest = (HttpWebRequest)WebRequest.Create(requestedURL);
authRequest.ContentType = "application/x-www-form-urlencoded";
authRequest.Method = "POST";
//Set content length to 0
authRequest.ContentLength = 0;
WebResponse authResponseTwitter = authRequest.GetResponse();

The ContentLength property contains the value to send as the Content-length HTTP header with the request.

Any value other than -1 in the ContentLength property indicates that the request uploads data and that only methods that upload data are allowed to be set in the Method property.

After the ContentLength property is set to a value, that number of bytes must be written to the request stream that is returned by calling the GetRequestStream method or both the BeginGetRequestStream and the EndGetRequestStream methods.

for more details click here

回答5:

Hey i'm using Volley and was getting Server error 411, I added to the getHeaders method the following line :

params.put("Content-Length","0");

And it solved my issue

回答6:

Change the way you requested the method from POST to GET ..

回答7:

Google search

2nd result

System.Net.WebException: The remote server returned an error: (411) Length Required.

This is a pretty common issue that comes up when trying to make call a REST based API method through POST. Luckily, there is a simple fix for this one.

This is the code I was using to call the Windows Azure Management API. This particular API call requires the request method to be set as POST, however there is no information that needs to be sent to the server.

var request = (HttpWebRequest) HttpWebRequest.Create(requestUri);
request.Headers.Add("x-ms-version", "2012-08-01"); request.Method =
"POST"; request.ContentType = "application/xml";

To fix this error, add an explicit content length to your request before making the API call.

request.ContentLength = 0;

回答8:

I had the same error when I imported web requests from fiddler captured sessions to Visual Studio webtests. Some POST requests did not have a StringHttpBody tag. I added an empty one to them and the error was gone. Add this after the Headers tag:

    <StringHttpBody ContentType="" InsertByteOrderMark="False">
  </StringHttpBody>

来源：https://stackoverflow.com/questions/18352190/why-i-get-411-length-required-error