ASP.NET Core 2.1 - Error Implementing MemoryCache

Question

I was following the steps given here to implement a MemoryCache in ASP.NET Core and when i start the application (dotnet run from command prompt), i get the following error.

System.InvalidOperationException: Unable to resolve service for type 'Microsoft.Extensions.Caching.Distributed.IDistributedCache' while attempting to activate 'Microsoft.AspNetCore.Session.DistributedSessionStore'.

What is confusing me is that i am using services.AddMemoryCache() and NOT services.AddDistributedMemoryCache(). Full stack trace is available in this bin. I have only these packages referenced

<PackageReference Include="Microsoft.AspNetCore.App" />
<PackageReference Include="Microsoft.AspNetCore.Razor.Design" Version="2.1.2" PrivateAssets="All" />
<PackageReference Include="System.Configuration.ConfigurationManager" Version="4.5.0" />

My Configure

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }

    app.UseStaticFiles();
    app.UseSpaStaticFiles();
    app.UseSession();
    app.UseCors(
        builder => builder
            .WithOrigins("http://localhost:4200")
            .AllowAnyHeader()
            .AllowAnyMethod()
            .AllowAnyOrigin()
            .AllowCredentials());
    app.UseMvc(
        routes =>
        {
            routes.MapRoute(
                "default",
                "api/{controller}/{action}/{id?}");
        });
}

ConfigureServices

public void ConfigureServices(IServiceCollection services)
{
    services.AddCors();
    services
        .AddMvcCore()
        .SetCompatibilityVersion(CompatibilityVersion.Version_2_1)
        .AddJsonFormatters();

    services.AddMemoryCache();

    // Angular files will be served from this directory
    services.AddSpaStaticFiles(configuration => { configuration.RootPath = "wwwroot"; });
    services.AddSession(
        options =>
        {
            // Set a short timeout for easy testing.
            options.IdleTimeout = TimeSpan.FromHours(1);
            options.Cookie.HttpOnly = true;
        });
}

Program.cs

  public static IWebHostBuilder CreateWebHostBuilder(string[] args)
    {
        return WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>();
    }

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

Answer 1

Seems to be that you try to inject IDistributedCache which is different from memory cache. Distributed cache will be using external services to store cache while memory cache is going to use servers memory.

As I said something,somewhere is using distributed cache. And that something is session

From that page

The default session provider in ASP.NET Core loads session records from the underlying IDistributedCache

Answer 2

Simply adding services.AddMemoryCache() after services.AddControllers() worked for me.