Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.SpaServices.Webpack;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

namespace msal_netcore_angular
{
    public class Startup
    {
        public Startup(IConfiguration configuration, IHostingEnvironment env)
        {
            Configuration = configuration;
            Environment = env;
        }

        public IConfiguration Configuration { get; }
        public IHostingEnvironment Environment { get; private set; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();

            services.AddAzureB2CAuthentication(Configuration["Jwt:Policy"],
                                               Configuration["Jwt:Tenant"],
                                               Configuration["Jwt:Audience"],
                                               Environment.IsDevelopment());
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app)
        {
            if (Environment.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions
                {
                    HotModuleReplacement = true
                });
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseAuthentication();

            app.UseStaticFiles();

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

                routes.MapSpaFallbackRoute(
                    name: "spa-fallback",
                    defaults: new { controller = "Home", action = "Index" });
            });
        }
    }
}