Microsoft.AspNetCore.Identity.IdentityError when attempting registration

Question

I'm implementing a simple authentication system with ASP.NET Core Identity using only username and password. When I call Register action, I get the error mentioned in the title.

Below the code which is associated with registration.

Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
   services.AddDbContext<AppDbContext>(options => 
   options.UseSqlServer(_configuration.GetConnectionString("Default")));
   services.AddIdentity<IdentityUser, 
   IdentityRole().AddEntityFrameworkStores<AppDbContext>();`

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseAuthentication();
}

AccountController.cs:

public class AccountController : Controller
{
    private readonly UserManager<IdentityUser> _userManager;
    private readonly SignInManager<IdentityUser> _signInManager;

    public AccountController(UserManager<IdentityUser> userManager, 
    SignInManager<IdentityUser> signInManager)
    {
        _userManager = userManager;
        _signInManager = signInManager;
    }
    public IActionResult Register()
    {
        return View();
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    [AllowAnonymous]
    public async Task<IActionResult> Register(RegistrationViewModel registrationViewModel)
    {
        if (ModelState.IsValid)
        {
            var user = new IdentityUser {UserName = registrationViewModel.UserName};
            var result = await _userManager.CreateAsync(user, registrationViewModel.Password);

            if (result.Succeeded)
                return RedirectToAction("Index", "Home");
            var errors = result.Errors;
            var message = string.Join(", ", errors);
            ModelState.AddModelError("", message);
        }

        return View(registrationViewModel);
    }

RegistrationViewModel.cs:

public class RegistrationViewModel
{
    [Required]
    [Display(Name = "User name")]
    public string UserName { get; set; }
    
    [Required]
    [DataType(DataType.Password)]
    public string Password { get; set; }
}

Registerm.cshtml:

@model RegistrationViewModel

<form asp-controller="Account" asp-action="Register" method="post" class="form-horizontal" role="form">

<div asp-validation-summary="All" class="text-danger"></div>

<div class="form-group">
    <label asp-for="UserName" class="col-md-2 control-label"></label>
    <div class="col-md-10">
        <input asp-for="UserName" class="form-control" />
        <span asp-validation-for="UserName" class="text-danger"></span>
    </div>
</div>
<div class="form-group">
    <label asp-for="Password" class="col-md-2 control-label"></label>
    <div class="col-md-10">
        <input asp-for="Password" class="form-control" />
        <span asp-validation-for="Password" class="text-danger"></span>
    </div>
</div>
<div class="form-group">
    <div class="col-md-offset-2 col-md-10">
        <input type="submit" class="btn btn-primary" value="Register" />
    </div>
</div>

`

As far as I know, such error occurs when the login is already associated with account, however, the table which is supposed to store all the users' data is empty.

Answer 1

Try using this to get a better error message. Your toString on Errors is just returning the objects type not whats in it.

var message =  string.Join(", ", response.Errors.Select(x => "Code " + x.Code + " Description" + x.Description));