public class Startup {    
public void ConfigureServices(IServiceCollection services)    {     
 services.AddSession(options =>        {       
     options.IdleTimeout = TimeSpan.FromMinutes(30);   
         options.Cookie.HttpOnly = true;   
         options.Cookie.IsEssential = true;   
     });         
  }   
  public void Configure(IApplicationBuilder app, IWebHostEnvironment env)    {        
     app.UseSession();         
   } }