AutoFac / .NET Core - Register DBcontext

I think that the problem is that you're trying to register MyContext() using AsImplementedInterfaces(). This is not how DbContext are getting registered usually. You should register and resolve class itself.

Another simple solution for Autofac version 4.8.1

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc().AddControllersAsServices();

        services.AddDbContext<MyContext>(options => options.UseSqlServer(Configuration.GetConnectionString("ConnectionStrings:MyConnection:ConnectionString")));

        var builder = new ContainerBuilder();

        builder.Populate(services);

        //...
        // Your interface registration
        //...

        builder.Build(Autofac.Builder.ContainerBuildOptions.None);
    }

I use Autofac to register both HttpContextAccessor and DbContext.

builder
    .RegisterType<HttpContextAccessor>()
    .As<IHttpContextAccessor>()
    .SingleInstance();

builder
    .RegisterType<AppDbContext>()
    .WithParameter("options", DbContextOptionsFactory.Get())
    .InstancePerLifetimeScope();

DbContextOptionsFactory

public class DbContextOptionsFactory
{
    public static DbContextOptions<AppDbContext> Get()
    {
        var configuration = AppConfigurations.Get(
            WebContentDirectoryFinder.CalculateContentRootFolder());

        var builder = new DbContextOptionsBuilder<AppDbContext>();
        DbContextConfigurer.Configure(
            builder, 
            configuration.GetConnectionString(
                AppConsts.ConnectionStringName));

        return builder.Options;
    }
}

DbContextConfigurer

public class DbContextConfigurer
{
    public static void Configure(
        DbContextOptionsBuilder<AppDbContext> builder, 
        string connectionString)
    {
        builder.UseNpgsql(connectionString).UseLazyLoadingProxies();
    }
}