Solved: Unable to resolve service for type microsoft.extensions.logging.ilogger

The Problem

A runtime error is triggered when using the Microsoft ILogger class in your .Net applications.

System.InvalidOperationException: ‘Unable to resolve service for type ‘Microsoft.Extensions.Logging.ILogger’

Common Steps to Reproduce

Configuration 1

Console application Main configuration

var services = new ServiceCollection()
    .AddLogging(logging => logging.AddConsole())
    .BuildServiceProvider();

Class implementation

private readonly ILogger _logger;
    
public MyService(ILogger logger)
{
    _logger = logger;
}

public void Execute()
{
    _logger.LogInformation("My Message");
}

The Solution

Configuration 1

ILogger is no longer registered by default but ILogger<T> is.

Incorrect implementation

private readonly ILogger _logger;
    
public MyService(ILogger logger)
{
    _logger = logger;
}

public void Execute()
{
    _logger.LogInformation("My Message");
}

Correct implementation

private readonly ILogger _logger;
    
public MyService(ILogger<MyService> logger)
{
    _logger = logger;
}

public void Execute()
{
    _logger.LogInformation("My Message");
}

Using Logger in Startup.cs or Main.cs

Create a generic class to use with ILogger

public class ApplicationLogger
{
}

Use ILogger with generic class in Startup or Main

public void ConfigureServices(IServiceCollection services)
{
    var serviceProvider = services.BuildServiceProvider();
    var logger = serviceProvider.GetService<ILogger<ApplicationLogger>>();

    //Add Singleton if you want to use Generic class logger in place of ILogger<T>
    services.AddSingleton(typeof(ILogger), logger);
}

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