Amazon web services – Basic .NET WebAPI hosted in AWS Lambda failing to construct controller

I created a new .NET 6 WebAPI solution, with the default WeatherForecastController class. The only thing I changed in the project is to install Amazon.AspNetCoreLambda.Hosting, and add the following line in my Program.cs file:

builder.Services.AddAWSLambdaHosting(LambdaEventSource.HttpApi);

I built the solution, zipped the files, and deployed it to an AWS Lambda. The error I’m getting in the logs is:

System.MissingMethodException: Cannot dynamically create an instance of type 'Example.Controllers.WeatherForecastController'. Reason: No parameterless constructor defined.

The controller is unchanged and looks like this:

using Microsoft.AspNetCore.Mvc;

namespace Example.Controllers;

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
    private static readonly string[] Summaries = new[]
    {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

    private readonly ILogger<WeatherForecastController> _logger;

    public WeatherForecastController(ILogger<WeatherForecastController> logger)
    {
        _logger = logger;
    }

    [HttpGet(Name = "GetWeatherForecast")]
    public IEnumerable<WeatherForecast> Get()
    {
        return Enumerable.Range(1, 5)
            .Select(
                index => new WeatherForecast
                {
                    Date = DateTime.Now.AddDays(index),
                    TemperatureC = Random.Shared.Next(-20, 55),
                    Summary = Summaries[Random.Shared.Next(Summaries.Length)]
                })
            .ToArray();
    }
}

The Program.cs file looks like this:

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddAWSLambdaHosting(LambdaEventSource.HttpApi);

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();

The AWS Lambda is set up with the following configuration:

• Hander: Example::Example.Controllers.WeatherForecastController::Get
• Runtime: dotnet6

Runtime: dotnet6

I can’t see what step I’m missing as I’ve been following tutorials online and can’t get it to work.

What am I missing?