.net core – _userManager.CreateAsync returns null when it is not

I'm trying to connect to a university project and create my own member table instead of the application user because I do not want any other attributes. This is my model.

        member of the public class
{
public int Id {get; together; }
public string UserName {get; together; }
public string Name {get; together; }
public string Last name {get; together; }
public channel Email {get; together; }
public string Password {get; together; }

}

And here is the model of view;

Public class RegisterViewModel
{
    [Required]
    [EmailAddress]
    [Display(Name = "Email")]
    
    
    
    public channel Email {get; together; }

    [Required]
    [Display(Name = "Name")]
    
    
    
    public string Name {get; together; }

    [Required]
    [Display(Name = "Surname")]
    
    
    
    public string Last name {get; together; }

    [Required]
    [StringLength(100, ErrorMessage = "The {0} must be at least {2} and at max {1} characters long.", MinimumLength = 6)]
    [DataType(DataType.Password)]
    [Display(Name = "Password")]
    
    
    
    public string Password {get; together; }

    [DataType(DataType.Password)]
    [Display(Name = "Confirm password")]
    [Compare("Password", ErrorMessage = "The password and confirmation password do not match.")]
    
    
    
    public string ConfirmPassword {get; together; }
}

And register the controller;

[HttpGet]
    [AllowAnonymous]
    
    
    
    Public registry IActionResult (string returnUrl = null)
{
ViewData["ReturnUrl"] = returnUrl;
return See ();
}

    [HttpPost]
    [AllowAnonymous]
    [ValidateAntiForgeryToken]
    
    
    
    asynchronous public task Register (RegisterViewModel template, returnUrl = null string)
{
ViewData["ReturnUrl"] = returnUrl;
if (ModelState.IsValid)
{
var user = new member {UserName = model.Email, Email = model.Email, Name = model.Name, Name = model.Surname};
var result = wait _userManager.CreateAsync (user, model.Password);
if (result.successed)
{
_logger.LogInformation ("The user has created a new account with a password.");



wait _signInManager.SignInAsync (user, isPersistent: false);
_logger.LogInformation ("The user has created a new account with a password.");
return RedirectToLocal (returnUrl);
}

}

// If we got there, something failed, redisplay the form
return the view (model);
}

the problem is here

var result = wait _userManager.CreateAsync (user, model.Password);

that gives an error that says

                    var result = wait _userManager.CreateAsync (user, model.Password);
NullReferenceException: The reference to an object is not defined on an instance of an object.

I put a breaking point to see if it is zero but it is not the case. I can not create a member this way. What error did I make here?