Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using ProjektSpotkaniaGrupTematycznych.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace ProjektSpotkaniaGrupTematycznych
{
    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.AddDbContext<ApplicationDbContext>(options =>
                options.UseSqlServer(
                    Configuration.GetConnectionString("DefaultConnection")));


            services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
                .AddEntityFrameworkStores<ApplicationDbContext>();
            services.AddRazorPages();

            services.Configure<IdentityOptions>(options =>
            {
                // Password settings.
                options.Password.RequireDigit = true;
                options.Password.RequireLowercase = true;
                options.Password.RequireNonAlphanumeric = false;
                options.Password.RequireUppercase = true;
                options.Password.RequiredLength = 6;
                options.Password.RequiredUniqueChars = 0;

                // Lockout settings.
                options.Lockout.DefaultLockoutTimeSpan = TimeSpan.FromMinutes(5);
                options.Lockout.MaxFailedAccessAttempts = 5;
                options.Lockout.AllowedForNewUsers = true;

                // User settings.
                options.User.AllowedUserNameCharacters =
                "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+";
                options.User.RequireUniqueEmail = false;
            });
            /*
            services.AddDbContext<ProjektSpotkaniaGrupTematycznychContext>(options =>
                    options.UseSqlServer(Configuration.GetConnectionString("ProjektSpotkaniaGrupTematycznychContext")));*/
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapRazorPages();
            });
        }
    }
}