Unable to resolve service for type 'Microsoft.Extensions.Logging.ILogger`1[WebApplication1.Startup]'

Question

I created an ASP.NET Core 3.0 Web Application with the default template in Visual Studio 2019 Preview 2.2 and tried to inject an ILogger in Startup:

namespace WebApplication1
{
    public class Startup
    {
        private readonly ILogger _logger;

        public Startup(IConfiguration configuration, ILogger<Startup> logger)
        {
            Configuration = configuration;
            _logger = logger;
        }
        // ...
    }
}

In Program.cs I also call the ConfigureLogging() method:

namespace WebApplication1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.ClearProviders();
                    logging.AddConsole();
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}

It works in ASP.NET Core 2.x but in ASP.NET Core 3 it fails with the following error:

System.InvalidOperationException: Unable to resolve service for type 'Microsoft.Extensions.Logging.ILogger`1[WebApplication1.Startup]' while attempting to activate 'WebApplication1.Startup'.
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters)
   at Microsoft.AspNetCore.Hosting.Internal.GenericWebHostBuilder.UseStartup(Type startupType, HostBuilderContext context, IServiceCollection services)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Hosting.Internal.GenericWebHostBuilder.<>c__DisplayClass13_0.<UseStartup>b__2(IApplicationBuilder app)
   at Microsoft.AspNetCore.Server.IIS.Core.IISServerSetupFilter.<>c__DisplayClass2_0.<Configure>b__0(IApplicationBuilder app)
   at Microsoft.AspNetCore.HostFilteringStartupFilter.<>c__DisplayClass0_0.<Configure>b__0(IApplicationBuilder app)
   at Microsoft.AspNetCore.Hosting.Internal.GenericWebHostService.StartAsync(CancellationToken cancellationToken)

Any idea on what is causing this behavior?

---

Below the full Program.cs and Startup.cs files from the default "Web Application" template, only logging was added.

Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace WebApplication1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.ClearProviders();
                    logging.AddConsole();
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}

Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace WebApplication1
{
    public class Startup
    {
        private readonly ILogger _logger;
        public Startup(IConfiguration configuration, ILogger<Startup> logger)
        {
            Configuration = configuration;
            _logger = logger;
        }

        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.AddTransient(typeof(ILogger<>), (typeof(Logger<>)));

            services.AddMvc()
                .AddNewtonsoftJson();
        }

        // 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();
            }
            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.UseStaticFiles();

            app.UseRouting(routes =>
            {
                routes.MapApplication();
            });

            app.UseCookiePolicy();

            app.UseAuthorization();
        }
    }
}

Ursulaursulette

I think you should be using ILoggerFactory instead of ILogger directly? – Dental

I get the same type of error with an ILoggerFactory. – Ursulaursulette

Do you call WebHostBuilder().ConfigureLogging(...)? – Toadeater

I do not but I think it's fine for the purpose of this test, it should use the default logging settings right? – Ursulaursulette

Can you share your Startup or Program.cs ? – Kettledrum

I just added it. It's basically the default ASP.NET Core 3.0 "Web Application" template, I just tried to inject an ILogger. – Ursulaursulette

Does this answer your question? Unable to resolve ILogger from Microsoft.Extensions.Logging – Calvaria

Answer 1

Unfortunately, it's not possible to inject ILogger into Startup.cs in ASP.NET Core 3.0 anymore.

https://learn.microsoft.com/en-us/azure/azure-monitor/app/ilogger#capture-ilogger-logs-from-startupcs-and-programcs-in-aspnet-core-apps

Note

In ASP.NET Core 3.0 and later, it is no longer possible to inject ILogger in Startup.cs and Program.cs. See https://github.com/aspnet/Announcements/issues/353 for more details.

EDIT: A possible way of doing logging inside the Configure method in Startup.cs would be:

            using (var logScope = app.ApplicationServices.CreateScope())
            {
                var logger = logScope.ServiceProvider.GetService<ILogger<Startup>>();
                logger.LogInformation("Some information");
            }

Phenazine

So... what do we pass in to services that need an ILogger from startup? – Harassed

@Harassed I added a way of doing that inside the Configure() method. – Phenazine

Answer 2

This can be solved by registering the ILogger manually to use the Startup class as type.

Example:

public void ConfigureServices(IServiceCollection services)
{
    // Normal AddLogging
    services.AddLogging();

    // Additional code to register the ILogger as a ILogger<T> where T is the Startup class
    services.AddSingleton(typeof(ILogger), typeof(Logger<Startup>)); 
  
    // ...
}

Warfare

Only this solution worked for me on .NET Core 3.1 – Tansy

Answer 3

If you want to log things after the Configure() has been called, you can still inject the ILogger via method injection (as opposed to the preferred constructor injection:

public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILogger<TStartup> logger)
{
     _logger = logger;
     ...
}

Logistic

How? I get The ConfigureServices method must either be parameterless or take only one parameter of type IServiceCollection – Thickness

Answer 4

Since dotnet 3.0, web applications use IHostBuilder instead of IWebHostBuilder. So it is no longer possible to directly inject an ILogger in the Startup class.

https://github.com/dotnet/docs/issues/14900

You can get around this by directly creating your logger for the Startup class in your builder.

Program.cs

public class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args)
                .Build()
                .Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args)
    {
        return Host.CreateDefaultBuilder(args)
                   .ConfigureLogging(AppLoggingConfiguration)
                   .ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); })
                   .UseWindowsService();
    }

    public static void AppLoggingConfiguration(ILoggingBuilder loggingBuilder)
    {
        loggingBuilder.ClearProviders();
        loggingBuilder.AddDebug();
        loggingBuilder.AddConsole();
        loggingBuilder.AddEventLog(new EventLogSettings
                                   {
                                           SourceName = "MySourceName",
                                           LogName = "Application",
                                   });
    }
}

Startup.cs

public class Startup
{
    private readonly ILogger<Startup> _logger;

    public Startup(IConfiguration configuration)
    {
        this.Configuration = configuration;
        var lf = LoggerFactory.Create(Program.AppLoggingConfiguration);
        _logger = lf.CreateLogger<Startup>();
    }

    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)
    {
                    
        /// ...    
        _logger.LogInformation("Hello startup");
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
      /// ...    
    }
}

Bynum

Answer 5

This issue is related with IHostBuilder.

For a temp workaround, I suggest you try IWebHost to replace IHostBuilder.

Change your Program.cs like

public class Program
{
    public static void Main(string[] args)
    {           
        BuildWebHost(args).Run();
    }
    public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .ConfigureLogging(logging =>
                {
                    logging.ClearProviders();
                    logging.AddConsole();
                })
                .Build();      
}

Heroics

While this does allow the app to launch, you just end up with errors for "Unable to resolve service for type 'Microsoft.Extensions.Logging.ILogger' while attempting to activate '<type>'" It doesn't fix the issue. – Guidance

Answer 6

Did you have using ServiceCollection to register the Logger yet! It's should be here.

serviceProvider.AddTransient(typeof(ILogger<>), (typeof(Logger<>));

or you put, this is sample for Program.cs

public class Program  
{  
    public static void Main(string[] args)  
    {  
        BuildWebHost(args).Run();  
    }  

    public static IWebHost BuildWebHost(string[] args) =>  
        WebHost.CreateDefaultBuilder(args)  
            .ConfigureLogging(logging => logging.SetMinimumLevel(LogLevel.Warning))  
            .UseStartup<Startup>()  
            .Build();  
}  

Uncommonly

Thanks for your answer, but it does not work either. – Ursulaursulette