Httpclient POST to web API returns 400 bad request

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C#

WPF

WebAPI

.NET-Core

I am trying to post captured image from WPF to WebApi method using HttpClient but i am getting 400 BAD REQUEST error.
I have tried in google but unable to resolve the issue. does anyone help me.
Below is the code in WPF

private async void btnLogin_Click(object sender, RoutedEventArgs e)
        {

            string FileName = 
            System.IO.Path.GetFullPath("../../captured_images") + 
            "//captured_image" + DateTime.Now.Day.ToString() + 
            DateTime.Now.Month.ToString() + DateTime.Now.Year.ToString() + 
            DateTime.Now.Second.ToString() + ".jpg";

            var encoder = new PngBitmapEncoder();
            encoder.Frames.Add(BitmapFrame.Create((BitmapSource)image.Source));
            using (FileStream stream = new FileStream(FileName, 
            FileMode.Create))
                encoder.Save(stream);

            string CASAAuthResponse = await 
            CASSecurity.GetAuthenticationToken();

            CASAuthTokenResponse techSeeTokenResponse = 
            JsonConvert.DeserializeObject<casauthtokenresponse> 
            (CASAAuthResponse);

           
          
                        
                    
		  HttpContent fileStreamContent = new StreamContent(File.OpenRead(FileName));
                  
                    using (var client1 = new HttpClient())
                    using (var formData = new MultipartFormDataContent())
                    {
                        client1.DefaultRequestHeaders.Add("Authorization", "Bearer " + token);

                        formData.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");

                        formData.Add(fileStreamContent, "face", 
     Path.GetFileName(FileName));
                     
                        var response = await 
    client1.PostAsync(CASIdentifyFaceUrl, formData);
                        if (!response.IsSuccessStatusCode)
                        {
                            return null;
                        }
                        
                    }

            

        }

Server Web api:

[HttpPost]
      [Route("identify")]
   
    public async Task<iactionresult> Identify(IFormFile face)
    {
        Guid temporaryUsername = Guid.Empty;
        using (var faceStream = face.OpenReadStream())
        {
            temporaryUsername = await verifyBusiness.IdentifyUser(faceStream, 
         new Guid(Requester.ClientId));
        }

        return Ok(temporaryUsername);
    }

> And i am getting error as descibed below:

{StatusCode: 400,
> ReasonPhrase: 'Bad Request', Version: 1.1, Content:
> System.Net.Http.StreamContent, Headers: { Transfer-Encoding: chunked
> Strict-Transport-Security: max-age=2592000 Date: Thu, 20 Jun 2019
> 11:13:28 GMT Set-Cookie:
> ARRAffinity=4cbc3e777eee0146fcbb9f695794b29417cc953731f6f8f581457a1d7cd7aa14;Path=/;HttpOnly;Domain=cas-qa.tempdata.net
> Server: Kestrel X-Powered-By: ASP.NET Content-Type:
> application/json; charset=utf-8 }}

What I have tried:

I HAVE TRIED DIFERRENT TRIAL AND ERRORS BUT NONO WORKING