来自Asp.Net Web Api Post的反应奇怪

Question

我有一个像以下

的Asp.Net Web Api

public async Task<IHttpActionResult> Post(Guid id, OrganisationModel model)
{
    try
    {       
        _orgService.AddNewOrganisationToParent(newOrg, org);
        await Context.SaveChangesAsync();
        return Ok(newOrg.Id);
    }
    catch (Exception ex)
    {
        Log.ErrorFormat("Problem creating new organisation {0}. Error {1}", UserId, ex);
        return InternalServerError(ex);
   }
}

当我从另一个Asp.Net Web应用程序使用以下内容调用它时;

            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            var newOrg = Newtonsoft.Json.JsonConvert.SerializeObject(new
            {
                name = systemTree.Name,
                type = 0
            });

            var content = new StringContent(newOrg.ToString(), Encoding.UTF8, "application/json");           
            var newOrgId = Guid.Empty;

            using (var response = await client.PostAsJsonAsync(orgEndpoint + orgId, content))
            {
                response.EnsureSuccessStatusCode();
                newOrgId = response.Content.ReadAsAsync<Guid>().Result;
            }

响应很奇怪，显示的代码抛出异常“exceptionMessage”：“无法将索引3处的字节[B4]从指定的代码页转换为Unicode。”，

如果我将其作为字符串阅读，我会得到以下内容

“SJN4OMN4MIK2M574Ե0 H6500H1NL2J4IR \ U0002 \ 0”

我有什么遗失的吗？提前谢谢。