密码的失败验证逻辑时如何读取验证错误消息

在我的IdentityConfig.cs中

   manager.PasswordValidator = new PasswordValidator
        {
            RequiredLength = 6,
            RequireNonLetterOrDigit = true,
            RequireDigit = true,
            RequireLowercase = true,
            RequireUppercase = true,
        };

在我的Web MVC UI中，这是我的操作方法

HttpResponseMessage responsePost = GlobalVariables.WebApiClient.PostAsJsonAsync("Account/Register", registerBindingModel).Result;
        if (responsePost.IsSuccessStatusCode)
        {
                ViewBag.Message = "Added";
        }
        else
        {
            ViewBag.Message = "Internal server Error: " + responsePost.ReasonPhrase;
        }

该代码有效。如果数据通过密码验证逻辑，则可以发布数据。但是，如果失败，它只会返回Internal server Error: Bad Request我的用户界面。但是，当我使用Postman测试它时，我可以从身份中看到错误消息。例Passwords must have at least one lowercase ('a'-'z').

此错误消息存储在HttpResponseMessage哪里？

注册的API方法

[AllowAnonymous]
    [HttpPost]
    [Route("Register")]
    public async Task<IHttpActionResult> Register(RegisterBindingModel model)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        var user = new ApplicationUser() { UserName = model.Email, Email = model.Email };

        IdentityResult result = await UserManager.CreateAsync(user, model.Password);

        if (!result.Succeeded)
        {
            return GetErrorResult(result);
        }

        return Ok();
    }

private IHttpActionResult GetErrorResult(IdentityResult result)
    {
        if (result == null)
        {
            return InternalServerError();
        }

        if (!result.Succeeded)
        {
            if (result.Errors != null)
            {
                foreach (string error in result.Errors)
                {
                    ModelState.AddModelError("", error);
                }
            }

            if (ModelState.IsValid)
            {
                // No ModelState errors are available to send, so just return an empty BadRequest.
                return BadRequest();
            }

            return BadRequest(ModelState);
        }

        return null;
    }