Unsupported Media Type http response when upload file using c# api.

Quite simple... I don't know what happened, but my method started to be invoked after I removed its parameter.

public HttpResponseMessage Post() 

So the working method for file upload using C# API controller is:

[HttpPost]
    public HttpResponseMessage Post()
    {
        var request = HttpContext.Current.Request;
        HttpResponseMessage result = null;
        logHelper.LogExecute(() =>
        {
            if (request.Files.Count == 0)
            {
                result = Request.CreateResponse(HttpStatusCode.BadRequest);
            }
            var resultFiles = new List<DatabaseFile>();
            using (var connection = sqlConnectionFactory.Create())
            using (var transaction = connection.BeginTransaction())
            {
                for (var i = 0; i < request.Files.Count; i++)
                {
                    var postedFile = request.Files[i];
                    var id = fileRepository.AddFile(postedFile.InputStream, postedFile.FileName, postFile.OrderId,
                                                    postFile.RootFolderName, connection, transaction);
                    resultFiles.Add(fileRepository.GetInfo(id, connection, transaction));
                }
                transaction.Commit();
            }
            result = Request.CreateResponse(HttpStatusCode.Created, resultFiles);
        });

        return result;
    }