I’m creating an ASP.NET Web API and MVC web app with SQL Server. It is working well, authorization is successful, but while I’m testing the login screen, if I enter something wrong like a wrong password, it is not returning a warning.

Here is my AccountController‘s login code

[HttpPost]
public async Task<ActionResult> Login(LoginViewModel model)
{
    if (ModelState.IsValid)
    {
        var content = new StringContent(JsonConvert.SerializeObject(model), Encoding.UTF8, "application/json");
        var response = await _httpClient.PostAsync("https://localhost:7180/api/auth/login", content);

        if (response.IsSuccessStatusCode)
        {
            var tokenResponse = await response.Content.ReadAsStringAsync();
            var token = JsonConvert.DeserializeObject<TokenResponse>(tokenResponse);

            if (HttpContext.Session != null)
            {
                HttpContext.Session.SetString("JWToken", token.Token);
            }
            else
            {
                ModelState.AddModelError("", "Session has not been configured.");
                return View(model);
            }

            TempData["Token"] = token.Token;
        }
        else
        {
            ModelState.AddModelError("", "Kullanıcı adı veya şifre 
               hatalı.");
            ViewData["ErrorMessage"] = "Kullanıcı adı veya şifre 
               hatalı.";
        }
        
    }

    return View(model);
}

And my login.cshtml view:

@page
@model WebApplication2.Models.LoginViewModel
@{
    ViewBag.Title = "Login";
}
<h2>Login</h2>

@using (Html.BeginForm("Login", "Account", FormMethod.Post))
{
    <div class="form-group">
        @Html.LabelFor(m => m.ADI)
        @Html.TextBoxFor(m => m.ADI, new { @class = "form-control" })
    </div>
    <div class="form-group">
        @Html.LabelFor(m => m.SOYADI)
        @Html.TextBoxFor(m => m.SOYADI, new { @class = "form-control" })
    </div>
    <div class="form-group">
        @Html.LabelFor(m => m.KULLANICI_ADI)
        @Html.TextBoxFor(m => m.KULLANICI_ADI, new { @class = "form-control" })
    </div>
    <div class="form-group">
        @Html.LabelFor(m => m.SIFRE)
        @Html.PasswordFor(m => m.SIFRE, new { @class = "form-control" })
    </div>
    <button type="submit" class="btn btn-primary">Login</button>

    @if (ViewData != null && ViewData.ModelState.ContainsKey(""))
    {
        <div class="alert alert-danger mt-3" role="alert">
            @Html.ValidationSummary(false, "", new { @class = "text-danger" })
        </div>
    }
        
}
@if (TempData["Token"] != null)
{
    <div class="alert alert-success mt-3" role="alert">
        Bearer Token:
        <button class="btn btn-info" id="toggleToken">Toggle Token</button>
        <div id="tokenContent" style="display: none;">
            <pre>@TempData["Token"]</pre>
        </div>
    </div>
    <div><p><a href="GetUsers">getallusers</a></p></div>
}

@section Scripts {
    <script>
        $(document).ready(function () {
            $('#toggleToken').click(function () {
                $('#tokenContent').slideToggle();
            });
        });
        
    </script>
}

I am expecting while entering the wrong name, surname, username or password or everything I want to see a warning about them…

Thanks a lot