Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Identity;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Project.Models;

namespace Project
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var host = CreateHostBuilder(args).Build();
            using(var scope = host.Services.CreateScope())
            {
                var serviceProvider = scope.ServiceProvider;
                try
                {
                    var userManager = serviceProvider.GetRequiredService<UserManager<User>>();
                    var roleManager = serviceProvider.GetRequiredService<RoleManager<IdentityRole>>();
                    var dbcontext = serviceProvider.GetRequiredService<ApplicationDBContext>();
                    Security.SecuritySeed.SeedData(userManager, roleManager,dbcontext);
                }
                catch { }
            }
            host.Run();

        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}