Static Visit HttpContext under Net5.0

Question

Recently I tried to upgrade one web project from .net core 2.2 to .net 5.0, but I run it with System.NullReferenceException of HttpContext.

And I have searched for long time without fixing it. Please kindly give your kind help. Many thanks!
The main code is as bellow:
1)HttpContextCore.cs:
public class HttpContextCore
{
public static HttpContext Current { get => AutofacHelper.GetService<IHttpContextAccessor>().HttpContext; }
}
2)Program.cs:
public class Program
{
public static void Main(string[] args)
{
CreateHostBuilder(args).Build().Run();
}

    /// <summary>  
    /// changed from IWebHostBuilder to IHostBuilder for .net5.0 upgrade in 2021-09-25  
    /// </summary>  
    /// <param name="args"></param>  
    /// <returns></returns>  
    public static IHostBuilder CreateHostBuilder(string[] args) =>  
        Host.CreateDefaultBuilder(args)  
            //Autofac for .net5.0 upgrade in 2021-09-25  
            .UseServiceProviderFactory(new AutofacServiceProviderFactory())  
            .ConfigureWebHostDefaults(webBuilder =>  
            {  
                webBuilder.UseStartup<Startup>();  
            });  
}  

3)Startup.cs:
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}

    public IConfiguration Configuration { get; }  

    //autofac for .net5.0 upgrade  
    public ILifetimeScope AutofacContainer { get; private set; }  

    // This method gets called by the runtime. Use this method to add services to the container.  
    public void ConfigureServices(IServiceCollection services)  
    {  
        services.AddDbContext<APPContext>(options =>  
        {  
            var connectionString = this.Configuration["ConnectionStrings:App"];    
            options.UseSqlServer(connectionString);  
        });  
        //Session  
        services.AddSession(options =>  
        {  
            options.IdleTimeout = TimeSpan.FromMinutes(240);  
            options.Cookie.HttpOnly = true;  
        });  

        #region upgrade net5.0   
        services.AddControllersWithViews(options =>  
        {  
            options.Filters.Add<CheckLoginFilters>();  
            options.Filters.Add<CheckPermissionFilters>();  
        })  
        .AddNewtonsoftJson(options => options.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver())  
        .SetCompatibilityVersion(CompatibilityVersion.Version_2_2);  
        #endregion  

        services.AddScoped<IHttpContextAccessor, HttpContextAccessor>();   
    }  

    /// <summary>  
    /// ConfigureContainer is where you can register things directly with Autofac that run after ConfigureServices.  
    /// </summary>  
    /// <param name="builder"></param>  
    public void ConfigureContainer(ContainerBuilder builder)  
    {  
        builder.RegisterModule(new DefaultModule());  
    }  

    /// <summary>  
    /// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.   
    /// </summary>  
    /// <param name="app"></param>  
    /// <param name="env"></param>  
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)  
    {  
        app.UseDeveloperExceptionPage();  

        //autofac   
        this.AutofacContainer = app.ApplicationServices.GetAutofacRoot();  

        app.UseStaticFiles();  
        app.UseCookiePolicy();  
        app.UseSession();  
        app.UseRouting();  
        app.UseEndpoints(endpoints =>  
        {  
            endpoints.MapControllerRoute(  
                name: "areas",  
                pattern: "{area:exists}/{controller=Home}/{action=Index}/{id?}");  
            endpoints.MapControllerRoute(  
                name: "default",  
                pattern: "{controller=Home}/{action=Index}/{id?}");  
        });  
        #endregion  
    }  
}  

Answer 1

This approach was always a hack. HttpContextAdapter uses thread Async Local storage to store the context. This means the caller must be on the same async call chain as a pipeline async call that sets the context.

You should refactor you code to not use a static accessor for HttpContext.