Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using AutoService.Data;
using AutoService.Data.Migrations;
using Microsoft.AspNetCore.Identity.UI.Services;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

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

            services.AddIdentity<ApplicationUser, IdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext>()
                .AddDefaultTokenProviders();
            //services.AddDefaultIdentity<ApplicationUser>()
            //    .AddEntityFrameworkStores<ApplicationDbContext>()
            //    .AddDefaultTokenProviders();
            services.AddTransient<IEmailSender, EmailSender>(i =>
                new EmailSender(
                    Configuration["EmailSender:Host"],
                    Configuration.GetValue<int>("EmailSender:Port"),
                    Configuration.GetValue<bool>("EmailSender:EnableSSL"),
                    Configuration["EmailSender:UserName"],
                    Configuration["EmailSender:Password"]
                )
            );

            // Not yet sure if this will help, tried it to attempt to solve an issue with the _ManageNav partial view not working
            // https://stackoverflow.com/a/46901806/1224964
            services.Configure<RazorViewEngineOptions>(o =>
            {
                // {2} is area, {1} is controller,{0} is the action    
                o.ViewLocationFormats.Clear();
                o.ViewLocationFormats.Add("/Controllers/{1}/Views/{0}" + RazorViewEngine.ViewExtension);
                o.ViewLocationFormats.Add("/Controllers/Shared/Views/{0}" + RazorViewEngine.ViewExtension);

                // Untested. You could remove this if you don't care about areas.
                o.AreaViewLocationFormats.Clear();
                o.AreaViewLocationFormats.Add("/Areas/{2}/Controllers/{1}/Views/{0}" + RazorViewEngine.ViewExtension);
                o.AreaViewLocationFormats.Add("/Areas/{2}/Controllers/Shared/Views/{0}" + RazorViewEngine.ViewExtension);
                o.AreaViewLocationFormats.Add("/Areas/Shared/Views/{0}" + RazorViewEngine.ViewExtension);
            });

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

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                app.UseHsts();
            }

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

            app.UseAuthentication();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}