System.NullReferenceException C# WebApi?

Question

.NET

I am implementing a simple .net console application that should generate and return responses to web api requests.
When accessed, it generates the following error:
System.Web.Http.SelfHost.HttpSelfHostServer.ProcessRequestContext
(ChannelContext channelContext, RequestContext requestContext) in System.Web.Http.SelfHost.Main
code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Web.Http;
using System.Web.Http.SelfHost;
using System.Threading;

namespace Stub
{
    class Program
    {
        public static meteo_ptog curr_obj = new meteo_ptog();
        static  void Main(string[] args)
        {
            //Конфигурируем запускаем сервак 
            var selfHostConfiguraiton = new HttpSelfHostConfiguration("http://127.0.0.1:5555");
            selfHostConfiguraiton.Routes.MapHttpRoute(name: "DefaultApiRoute", routeTemplate: "api/{controller}", defaults: null);
            using (var server = new HttpSelfHostServer(selfHostConfiguraiton))
            {
                server.OpenAsync().Wait();
            }
            //Периодически генерим показатели 
            while (true)
            {
                curr_obj.get_params();
                curr_obj.next_time();
                Console.WriteLine("Reading params OK Iteration" + curr_obj.iterat + "time " + curr_obj.time);
                Thread.Sleep(20000);
               }
    }
}

The indicator class Meteo_ptog will be only (if necessary, I will lay out additionally)
Interface to it:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ESP_Stub
{
   public class IParam
    {
        public int time { get; set; }
        public int iterat { get; set; }
        public string param_1 { get; set; }
        public string param_2 { get; set; }
        public string param_3 { get; set; }
        public string version { get; set; }
        public string cordinates { get; set; }
    }
}

And the controller itself:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace ESP_Stub
{
    public class ProductController : ApiController
    {

        public IList<IParam> GetAllProducts()
        {
            return new List<IParam>(){
                    new IParam(){time=Program.curr_obj.time,
                        iterat =Program.curr_obj.iterat,
                        param_1=Program.curr_obj.param_1,
                        param_2=Program.curr_obj.param_2,
                        param_3=Program.curr_obj.param_3,
                        version=Program.curr_obj.version,
                        cordinates=Program.curr_obj.cordinates
                  }

        };
        }

       

        // POST api/<controller>
        public void Post(string value)
        {
        }

        // PUT api/<controller>/5
        public void Put(int id, string value)
        {
        }

        // DELETE api/<controller>/5
        public void Delete(int id)
        {
        }
    } }

Please help me figure it out
Ps The application should constantly take indicators, and not wait for requests via WebAPI

Answer 1

1. public class IParam - by name it is an interface. Rename, otherwise you will be confused yourself and others.
2.

// POST api/<controller>
// PUT api/<controller>/5
// DELETE api/<controller>/5

where is it taught??
do it right:

[HttpGet, Route("~/api/Products")
public IList<IParam> GetAll()
{
}
[HttpGet, Route("~/api/Products/{id}")
public IParam Get(int id)
{
}
[HttpPost, Route("~/api/Products")]
public void Post(string value)
{
}
[HttpPut, Route("~/api/Products/{id}")]
public void Put(int id, string value)
{
}
[HttpDelete, Route("~/api/Products/{id}")]
public void Delete(int id)
{
}

3. "The application must constantly take indicators, and not wait for WebAPI calls"
and then why do you need to cross WebApi? let there be a console application or a slezhba that writes your indicators to the log / database.
and there will be a separate WebAPI site on ISS that can give this data from the log / database.