HttpClient not accepting Authorization headers (401 Unauthorized)?

Question

I am creating a Xamarin.Forms mobile app that targets Android with .NET Standard as my code sharing method. Unfortunately the API I'm consuming works in Postman but doesn't work in C# using HttpClient from System.Net.Http.

Postman request works using this header:

I have tried 3 different approaches but they all still return "401 unauthorized". I've also checked the INTERNET permission in my Android Manifest file.

HttpClient.DefaultRequestHeaders.Add("Authorization", "Token e2eeb1aa9f32eb0ekgn353b6fadb772");
HttpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Token", "e2eeb1aa9f32eb0ekgn353b6fadb772");
HttpClient.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", "Token e2eeb1aa9f32eb0ekgn353b6fadb772");

Adenoidectomy

Try to add a call to HttpClient.DefaultRequestHeaders.Clear(); to make sure there aren't any other headers in there. – Unlace

I have tried that as well to no avail. – Adenoidectomy

Also, "Token" seems strange. Normally this is "Bearer"? – Unlace

Yes normally it is Bearer but when I use Bearer it throws me an error. It only works (in Postman) by using Authorization: Token <Space> <Token Value> as the header. – Adenoidectomy

Did the solution in my answer work? – Sassoon

Answer 1

Try setting the header on the HttpRequestMessage:

request.Headers.Authorization = new 
    AuthenticationHeaderValue("Bearer","e2eeb1aa9f32eb0ekgn353b6fadb772");

Fronnia

This answer helped me today. I was setting authorization header on client.DefaultRequestHeaders level earlier which was not working. – Blob

Answer 2

Please make sure your HTTP request URL is correct or not. Sometimes you may need a trailing forwardslash ( '/' ). If you missed it in HTTP client, will not work but POSTMAN will .

Spacesuit

yep, because of that missing backslash I waste 1 hour of researching the 401 error message.............. – Avocation

Postman also is lenient with http vs https - in my case, C# needed to be using https. – Thick

think there is a typo in answer. backslash is this one - ' \ ' – Confect

Answer 3

In my case, was fixed when I set the basic authentication in the AuthenticationHeaderValue.

var authToken = Encoding.ASCII.GetBytes(_UserName + ":" + _Password);
client.DefaultRequestHeaders.Authorization= new AunthenticationHeaderValue("Basic", Convert.ToBase64String(authToken));

Lobe

Answer 4

The url I was calling was "http" and the server redirects it to https. Apparently this drops the headers. Didnt happen through postman !!

Solution: use httpS

Trimble

This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post. You can setup server to not redirect to https, so your solution is irrelevant. – Sassaby