configure_services.cs

       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.AddAntiforgery(o => o.SuppressXFrameOptionsHeader = true);
            services.AddDistributedMemoryCache();
            


            services.AddSession(options =>  // <--------
            {
                // Set a short timeout for easy testing.
                // options.IdleTimeout = TimeSpan.FromSeconds(10);
                options.Cookie.HttpOnly = true;
                options.Cookie.IsEssential = true; // make the session cookie Essential
            });




            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
        }