POST API C# Body mode file with content type - application/octet-stream

Question

Here is the JSON request as per POSTMAN I am having difficulty with posting file mode with content type as octet-stream. Wondering anyone have a sample code in C#: Here are the details:

POST API Headers :

"method": "POST",
"header": [
    {
        "key": "Content-Type",
        "value": "application/octet-stream",
        "type": "text"
    },
    {
        "key": "Content-Disposition",
        "value": "attachment; filename=\"sample.txt\"",
        "description": " ",
        "type": "text"
    }
]

Body :

"body": {
    "mode": "file",
    "file": {
        "src": "/C:/Users/kodurusa/Desktop/sample.txt"
    }

Here is my code

        client.DefaultRequestHeaders.Accept.Clear();

        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/octet-stream"));

       client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/octet-stream");
        client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Disposition", "attachment; filename=sample.pdf");
        
        string additionalUrl = _fileUploadSettings.Value.Url;
        string relativePath = string.Concat(apiEndPoint, additionalUrl);

        var serializerSettings = new JsonSerializerSettings();
        serializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
        var stringPayload = JsonConvert.SerializeObject(fileUpload, serializerSettings);

        var httpContent = new StringContent(stringPayload, Encoding.UTF8, "application/octet-stream");

        var response = await client.PostAsync(relativePath, httpContent);

I am getting response as 406

{StatusCode: 406, ReasonPhrase: '', Version: 1.1, Content: System.Net.Http.HttpConnectionResponseContent, Headers: { Date: Mon, 03 Jul 2023 22:01:35 GMT x-correlation-id: a624c396-6c3a-4388-b13b-da36b94cce0h x-trans-id: a7dc7de2-47db-4133-9883-5b24g35addf5 X-Content-Type-Options: nosniff x-xss-protection: 1; mode=block Cache-Control: no-store, must-revalidate, no-cache, max-age=0 Pragma: no-cache X-Frame-Options: DENY Strict-Transport-Security: max-age=15724800; includeSubDomains Content-Length: 0 Expires: 0 }} Content: {System.Net.Http.HttpConnectionResponseContent} Headers: {Date: Mon, 03 Jul 2023 22:01:35 GMT x-correlation-id: a624c396-6c3a-4388-b13b-da36b94cce0h x-trans-id: a7dc7de2-47db-4133-9883-5b24g35addf5 X-Content-Type-Options: nosniff x-xss-protection: 1; mode=block Cache-Control: no-store, must-revalidate, no-cache, max-age=0 Pragma: no-cache X-Frame-Options: DENY Strict-Transport-Security: max-age=15724800; includeSubDomains } IsSuccessStatusCode: false ReasonPhrase: "" RequestMessage: {Method: POST, RequestUri: 'https://XXXXXyyyyzzzz', Version: 1.1, Content: System.Net.Http.StringContent, Headers: {

Accept: application/octet-stream Request-Id: |131aba2e-4e0b36686b74f15c. Content-Type: application/octet-stream; charset=utf-8 Content-Length: 77 }} StatusCode: NotAcceptable TrailingHeaders: {} Version: {1.1}