Sorry for the bug. Please follow these steps to solve the error.

1. Open project with visual studio.

2. Open Controllers > AccountController.cs

3. Go to ResetPassword function, edit the code like below:

   [AllowAnonymous]
   public IActionResult ResetPassword(string code)
   {
       if (string.IsNullOrEmpty(code))
       {
           return View("Error");
       }
       else
       {
           ResetPasswordViewModel model = new ResetPasswordViewModel();
           model.Code = code;
           return View(model);
       }
   }
   

4. Go to Views > Account > ResetPassword.cshtml, inside @using, add @Html.HiddenFor(m=>m.Code)

   @using (Html.BeginForm("ResetPassword", "Account", new { ReturnUrl = ViewBag.ReturnUrl }, FormMethod.Post,null, new { @class = "form-horizontal", role = "form" }))
   {
   	@Html.HiddenFor(m=>m.Code)
   	@Html.AntiForgeryToken();
   }
   

5. Done, the reset password should be working now.