C# HttpClient Post with Authorization and JSON data - 401 Unauthorized

Question

trying to send a post request (works fine in postman) but keep getting 401 Unauthorised exception in C#. Here is my code:

var httpClient = new HttpClient();
var creds = string.Format("{0}:{1}", "username", "password");
var basicAuth = string.Format("Basic {0}", Convert.ToBase64String(Encoding.UTF8.GetBytes(creds)));
httpClient.DefaultRequestHeaders.Add("Authorization", basicAuth);

var requestMessage = new HttpRequestMessage(HttpMethod.Post, url);
requestMessage.Content = new StringContent(postData, Encoding.UTF8, "application/json");
requestMessage.Headers.Authorization = new AuthenticationHeaderValue("Basic", "encodedValue==");

var post = httpClient.SendAsync(requestMessage);
post.Wait();

same thing is happening when using HttpWebRequest:

var webReq = (HttpWebRequest)WebRequest.Create(url);
webReq.Headers.Add("Authorization","Basic encodedValue==");
webReq.Method = "POST";
webReq.ContentType = "application/json";

try
{
    using (var streamWriter = new StreamWriter(webReq.GetRequestStream()))
    {
        streamWriter.Write(json);
        streamWriter.Flush();
        streamWriter.Close();
    }

    var httpResponse = (HttpWebResponse)webReq.GetResponse();
    using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
    {
        response = streamReader.ReadToEnd();
    }
}

Does any one have any ideas what could I try? PS (encodedValue== is correctly encoded)

score 7 · Accepted Answer · answered Dec 11 '19 at 19:01

7

The HttpClient loses it's headers on redirections.

So make sure, that you use the correct API address. If your API doesn't allow insecure connections but you use "http://your-api-address.xy/" instead of "https://your-api-address.xy/" it will return a redirection and your client loses the headers.

answered Dec 11 '19 at 19:01

Tomsen

321
3
12

2

Hi this was correct, so what's been actually happening was that "https:/url" was redirected to "https:/url/" and during this action header was being lost. I switched off automatic redirections in Postman as mentioned here: https://stackoverflow.com/questions/56763018/is-there-a-way-to-retrieve-the-redirected-url-from-a-postman-response then followed the shown response - where I found out that there is "/" at the end! :) Thanks – Pete Kozak Dec 16 '19 at 13:09

score 2 · Answer 2 · edited Jul 05 '21 at 07:47

2

Please try this code

using (HttpClient client = new HttpClient())
{
    var byteArray = Encoding.ASCII.GetBytes("user:passowrd");

    client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));

    var response = client.SendAsync(object);
}

edited Jul 05 '21 at 07:47

Josef

2,869
2
22
23

answered Jul 04 '21 at 18:05

Rathinam Shanmugam

131
2
1

C# HttpClient Post with Authorization and JSON data - 401 Unauthorized

2 Answers2