startup.cs

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    this.ServiceProvider = app.ApplicationServices;
    loggerFactory.AddConsole(Configuration.GetSection("Logging"));
    loggerFactory.AddDebug();

    if (env.IsDevelopment())
    {
        loggerFactory.AddConsole(Configuration.GetSection("Logging"));
        loggerFactory.AddDebug();
        app.UseDeveloperExceptionPage();
        app.UseBrowserLink();
    }
    else
    {
        app.UseExceptionHandler("/Home/Error");
    }

    app.UseOAuthValidation();
    app.UseOpenIddict();
    app.Map("/api", apiApp =>
    {
        if (env.IsDevelopment())
        {
            apiApp.UseCors(builder =>
                builder.WithOrigins("http://localhost:4200")
                        .AllowAnyHeader()
                        .AllowAnyMethod()
                );
        }

        apiApp.UseOAuthValidation(options =>
        {
            options.Events = new OAuthValidationEvents
            {
                // Note: for SignalR connections, the default Authorization header does not work,
                // because the WebSockets JS API doesn't allow setting custom parameters.
                // To work around this limitation, the access token is retrieved from the query string.
                OnRetrieveToken = context =>
                {
                    context.Token = context.Request.Query["access_token"];

                    return Task.FromResult(0);
                }
            };
        });

        //apiApp.UseSignalR(router =>
        //{
        //    router.MapHub<ExamHub>("/exam-hub");
        //});

        //apiApp.UseSignalR2();
        apiApp.UseOpenIddict();
        apiApp.UseMvc(routes =>
        {
            // Matches requests that correspond to an existent controller/action pair
            routes.MapRoute(
                name: "default",
                template: "{controller}/{action}/{id?}");
        });
    });

    app.Use(async (context, next) =>
    {
        await next();

        if (context.Response.StatusCode == 404
            && !Path.HasExtension(context.Request.Path.Value))
        {
            context.Request.Path = "/index.html";
            await next();
        }
    });
    app.UseStaticFiles();
    app.UseDefaultFiles();
}