MVC Web API NET CORE 5.0 Google Auth: No webpage was found for the web address: https://localhost:44307/signin-google

Question

Just built a brand new web api, followed this example: https://docs.microsoft.com/en-us/aspnet/core/security/authentication/social/google-logins?view=aspnetcore-5.0 as best I could understand. Not using razor pages or a database. And had to add the following because it wouldn't run otherwise:

services.AddAuthentication(options =>
{
    options.DefaultAuthenticateScheme = GoogleDefaults.AuthenticationScheme;
    options.DefaultChallengeScheme = GoogleDefaults.AuthenticationScheme;
})

Created the auth token in https://console.cloud.google.com/apis/credentials, stored them locally, and set the redirect to https://localhost:44307/signin-google as suggested.

This is my complete code.

using Microsoft.AspNetCore.Authentication.Google;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;

namespace WebApplication3
{
    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.AddAuthentication(options =>
            {
                options.DefaultAuthenticateScheme = GoogleDefaults.AuthenticationScheme;
                options.DefaultChallengeScheme = GoogleDefaults.AuthenticationScheme;

            }).AddGoogle(options =>
            {                
                IConfigurationSection googleAuthNSection =
                Configuration.GetSection("Authentication:Google");

                options.ClientId = googleAuthNSection["ClientId"];
                options.ClientSecret = googleAuthNSection["ClientSecret"];

            });
            services.AddMvc(options =>
            {
                options.EnableEndpointRouting = false;
            });
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "WebApplication3", Version = "v1" });
            });
        }

        // 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.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "WebApplication3 v1"));
            }

            app.UseHttpsRedirection();
            app.UseRouting();
            app.UseStaticFiles();
            app.UseAuthorization();
            app.UseMvc();
        }
    }
}

And the controller:

using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using System.Security.Claims;

namespace WebApplication3.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class UserController : ControllerBase
    {
        [HttpGet]
        [Authorize]
        public string Get()
        {
            return User.FindFirst(ClaimTypes.Email)?.Value;
        }
    }
}

And this is the launchsettings.json

{
  "$schema": "http://json.schemastore.org/launchsettings.json",
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:6108",
      "sslPort": 44307
    }
  },
  "profiles": {
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "swagger",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "WebApplication3": {
      "commandName": "Project",
      "dotnetRunMessages": "true",
      "launchBrowser": true,
      "launchUrl": "swagger",
      "applicationUrl": https://localhost:5001;http://localhost:5000",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    }
  }
}

After authenticating with Google, I get this 404 error. The Middleware that handles the redirect is not working. What am I missing?

This localhost page can’t be found No webpage was found for the web address: https://localhost:44307/signin-google?state=CfDJ8AQzN35V4MFOkj0na0CgYAVyRcb43o1mYJ8O0-0OFiTiRbXtG4ACLk4IOEVRUP6cQ1B4Goxb6GWtDzDHKc6tsl-Hibm9CC9IyJCALL2Xj18HlmGNv6wmSUiQw8Dh8hJB6pPembsPHBdUmNFREHdU2uIQzGbUYsCIfH6kgNpqTysF0mWNov5BkxaPkzyknqUrmcrOt1_crcVPYzprhnjyxiPutE4Wk4EpvNE-TYeWP2V9&code=4%2F0AX4XfWjWkwE4_Uj-es9mmq29QVaWpcLbwhJ95r0CpNlfvLKKedTVnWZd1qlkIl8nCDvSOg&scope=email+profile+openid+https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fuserinfo.profile+https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fuserinfo.email&authuser=0&prompt=consent# HTTP ERROR 404

Answer 1

It's missing in Startup.cs:

app.UseAuthentication();