ASP.NET CORE 2.1 Identity has been registered

Question

I have problem with Identity ASP.net Core 2.1. I create Role in startup.cs. When running display error

AggregateException: One or more errors occurred. (No service for type 'Microsoft.AspNetCore.Identity.RoleManager`1[Microsoft.AspNetCore.Identity.IdentityRole]' has been registered.) System.Threading.Tasks.Task.Wait(int millisecondsTimeout, CancellationToken cancellationToken) System.Threading.Tasks.Task.Wait() ContosoUniversity.Startup.Configure(IApplicationBuilder app, IHostingEnvironment env, IServiceProvider serviceProvider) in Startup.cs + CreateRoles(serviceProvider).Wait(); Microsoft.AspNetCore.Hosting.ConventionBasedStartup.Configure(IApplicationBuilder app) Microsoft.AspNetCore.Server.IISIntegration.IISSetupFilter+<>c__DisplayClass4_0.b__0(IApplicationBuilder app) Microsoft.AspNetCore.HostFilteringStartupFilter+<>c__DisplayClass0_0.b__0(IApplicationBuilder app) Microsoft.AspNetCore.Hosting.Internal.AutoRequestServicesStartupFilter+<>c__DisplayClass0_0.b__0(IApplicationBuilder builder) Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()

Statup.cs file

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.EntityFrameworkCore;
using ContosoUniversity.Models;
using Microsoft.AspNetCore.Identity;
using ContosoUniversity.Areas.Identity.Data;

namespace ContosoUniversity
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;

        }
        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CookiePolicyOptions>(options =>
            {
                // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                options.CheckConsentNeeded = context => true;
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });

            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

            services.AddDbContext<SchoolContext>(options =>
                    options.UseSqlServer(Configuration.GetConnectionString("SchoolContext")));

            //services.AddIdentity<ContosoUniversityUser, IdentityRole>()
            //    .AddEntityFrameworkStores<IdentityContext>()
            //     .AddDefaultTokenProviders();


        }
        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, IServiceProvider serviceProvider)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseAuthentication();
            app.UseMvc();
            CreateRoles(serviceProvider).Wait();
        }
        public async Task CreateRoles(IServiceProvider serviceProvider)
        {

            //adding custom roles
            var RoleManager = serviceProvider.GetRequiredService<RoleManager<IdentityRole>>();
            //serviceProvider.GetService<RoleManager<IdentityRole>>();
            var UserManager = serviceProvider.GetRequiredService<UserManager<ContosoUniversityUser>>();
            string[] roleNames = { "Admin", "Manager", "Member" };
            IdentityResult roleResult;
            foreach (var roleName in roleNames)
            {
                var roleExist = await RoleManager.RoleExistsAsync(roleName);
                if (!roleExist)
                {
                    roleResult = await RoleManager.CreateAsync(new IdentityRole(roleName));
                }
            }
            var poweruser = new ContosoUniversityUser
            {
                UserName = Configuration.GetSection("UserSettings")["UserEmail"],
                Email = Configuration.GetSection("UserSettings")["UserEmail"]
            };

            string UserPassword = Configuration.GetSection("UserSettings")["UserPassword"];
            var _user = await UserManager.FindByEmailAsync(Configuration.GetSection("UserSettings")["UserEmail"]);

            if (_user == null)
            {
                var createPowerUser = await UserManager.CreateAsync(poweruser, UserPassword);
                if (createPowerUser.Succeeded)
                {
                    await UserManager.AddToRoleAsync(poweruser, "Admin");
                }
            }
        }
    }
}

Answer 1

You are trying to use asp.net-identity without registering it with your container.

In the configure-service method uncomment these lines

services.AddIdentity<ContosoUniversityUser, IdentityRole>();
        .AddEntityFrameworkStores<IdentityContext>()
        .AddDefaultTokenProviders();

Now the serviceprovider will know about these services because that extension method registers them for you.

Also don't forget to migrate your database so it knows about the user, roles and so on.