ASP.Net Identity: Unable to resolve service for type while attempting to activate

Hi,

Trying to add custom fields but the register page will not load.

InvalidOperationException: Unable to resolve service for type 
'Microsoft.AspNetCore.Identity.UserManager`1[ShoppingCart2023.Models.ApplicationUser]' 
while attempting to activate 'ShoppingCart2023.Areas.Identity.Pages.Account.Manage.IndexModel'.

here is the index:

using System.ComponentModel.DataAnnotations;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using ShoppingCart2023.Models;

namespace ShoppingCart2023.Areas.Identity.Pages.Account.Manage
{
    public class IndexModel : PageModel
    {
        private readonly UserManager<ApplicationUser> _userManager;
        private readonly SignInManager<ApplicationUser> _signInManager;

        public IndexModel(
            UserManager<ApplicationUser> userManager,
            SignInManager<ApplicationUser> signInManager)
        {
            _userManager = userManager;
            _signInManager = signInManager;
        }

        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        public string Username { get; set; }

        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        [TempData]
        public string StatusMessage { get; set; }

        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        [BindProperty]
        public InputModel Input { get; set; }

        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        public class InputModel
        {
            /// <summary>
            ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
            ///     directly from your code. This API may change or be removed in future releases.
            /// </summary>
            [Phone]
            [Display(Name = "Phone number")]
            public string? PhoneNumber { get; set; }
            [Required]
            public string? Name { get; set; }
            public string? Address { get; set; }
            public string? City { get; set; }
            public string? PinCode { get; set; }

        }

        private async Task LoadAsync(ApplicationUser user)
        {
            var userName = await _userManager.GetUserNameAsync(user);
            var phoneNumber = await _userManager.GetPhoneNumberAsync(user);

            Username = userName;

            Input = new InputModel
            {
                PhoneNumber = phoneNumber,
                Name = Input.Name,
                Address = Input.Address,
                City = Input.City,
                PinCode = Input.PinCode
            };
        }

        public async Task<IActionResult> OnGetAsync()
        {
            var user = await _userManager.GetUserAsync(User);
            if (user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }

            await LoadAsync(user);
            return Page();
        }

        public async Task<IActionResult> OnPostAsync()
        {
            var user = await _userManager.GetUserAsync(User);
            if (user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }

            if (!ModelState.IsValid)
            {
                await LoadAsync(user);
                return Page();
            }

            var phoneNumber = await _userManager.GetPhoneNumberAsync(user);
            if (Input.PhoneNumber != phoneNumber)
            {
                var setPhoneResult = await _userManager.SetPhoneNumberAsync(user, Input.PhoneNumber);
                if (!setPhoneResult.Succeeded)
                {
                    StatusMessage = "Unexpected error when trying to set phone number.";
                    return RedirectToPage();
                }
            }

            user.Name = Input.Name;
            user.Address = Input.Address;
            user.City = Input.City;
            user.PinCode = Input.PinCode;

            await _signInManager.RefreshSignInAsync(user);
            StatusMessage = "Your profile has been updated";
            return RedirectToPage();
        }
    }
}