Blazor WASM Hosted Authentication Null Reference Exception in IdentityServerBuilderConfigurationExtension

Question

I have a blazor WASM Hosted project using IdentityServer4 ( default from VS templates ). When I launch my application, however, I get the following error. Debugging shows that the options.Value.SigningCredential is null so the .Key is causing the NullReferenceException. So I am missing something, somewhere.

Here is the Client Program.cs

public static async Task Main(string[] args)
        {
            var builder = WebAssemblyHostBuilder.CreateDefault(args);
            //builder.RootComponents.Add<App>("#app");

            builder.Services.AddHttpClient("BBQFriend.API", client => client.BaseAddress = new Uri(builder.HostEnvironment.BaseAddress))
                .AddHttpMessageHandler<BaseAddressAuthorizationMessageHandler>();

            // Supply HttpClient instances that include access tokens when making requests to the server project
            builder.Services.AddScoped(sp => sp.GetRequiredService<IHttpClientFactory>().CreateClient("BBQFriend.API"));

            builder.Services.AddApiAuthorization();

            var baseAddress = new Uri("https://localhost:44395/api/");

            void RegisterTypedClient<TClient, TImplementation>(Uri apiBaseUrl)
                where TClient : class where TImplementation : class, TClient
            {
                builder.Services.AddHttpClient<TClient, TImplementation>(client =>
                {
                    client.BaseAddress = apiBaseUrl;
                });
            }

            RegisterTypedClient<ICountryService, CountryService>(baseAddress);          

            await builder.Build().RunAsync();
        }

Here is the Server Startup.cs

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)
        {
            //Register EntityFramework Core Datacontext for Dependency Injection
            services.AddDbContext<DataContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));            

            //Add common Identity Screens
            services.AddDefaultIdentity<ApplicationUser>(options => options.SignIn.RequireConfirmedAccount = true)
                .AddEntityFrameworkStores<DataContext>();

            //Set up IdentityServer
            services.AddIdentityServer()
                .AddApiAuthorization<ApplicationUser, DataContext>();

            services.AddAuthentication()
                .AddIdentityServerJwt();

            //Register Services for DirectNavigation
            services.AddScoped<ICountryService, CountryService>();

            //Register Repositories for Dependency Injection
            services.AddScoped<ICountryRepository, CountryRepository>();

            services.AddDatabaseDeveloperPageExceptionFilter();

            services.AddControllersWithViews();
            services.AddRazorPages();
        }

        // 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.UseWebAssemblyDebugging();
            }
            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.UseBlazorFrameworkFiles();
            app.UseStaticFiles();

            app.UseRouting();

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

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapRazorPages();
                endpoints.MapControllers();
                //endpoints.MapFallbackToFile("index.html");
                endpoints.MapFallbackToPage("/_Host");
            });
        }

And here is the applications DataContext.cs

public class DataContext : ApiAuthorizationDbContext<ApplicationUser>
    {
        public DataContext(DbContextOptions options, IOptions<OperationalStoreOptions> operationalStoreOptions) : base(options, operationalStoreOptions)
        {
            ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;
        }

        public DbSet<Country> Countries { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.ApplyConfiguration(new CountryConfiguration());

            base.OnModelCreating(modelBuilder);

        }
    }

Answer 1

Issue is that you are missing the client config values. As you are using builder.Services.AddApiAuthorization(); it tries to load configuration from default:

By default, configuration for the app is loaded by convention from _configuration/{client-id}. By convention, the client ID is set to the app's assembly name. This URL can be changed to point to a separate endpoint by calling the overload with options.