Web Development

1. For the web API, I have been making a call to the API's Test Controller's Test Method. If it succeeds, then I assume it's working, if not, then I assume the site isn't running.
2. For the SignalR API, I call a method called 'Connect()' via the hub and wait for ConnectionStateChanged to indicated Connection State = Connected. Problem is, this response may never come.

Hi to all,
 
I am having live web application, which some times log out due to post back in firefox only.
At that time Session become null and Log Out.
 
In Other browsers working fine. I am using Firefox 69.0.2 (Latest) version.
 
Log Out happnes into Live Clients or in Production server only. In web developement working fine.
I am having Old Web Application around 12 years old web site (Product) and successfully using 150+ clients.
 
Some clients facing this issue. I have checked at my end. Issue still persist in some pages of web site.
Any one faced same issue?
 
Is there any thing that i can check that issue in otherway ?
 
Thank You 

public class ApiSampleUploadController : ApiController
   {


       [HttpPost]
       public string Test(HttpPostedFileBase file )
       {

           return "Success";
       }


   }

@using (Html.BeginForm("Submit"))
 {
 /*code*/
     //FileUpload
       <div>
        <input type="file" name="file" id="uploadFile" />
      </div>
/*code*/
 }

$('#uploadFile').on("change", function () {
    var formdata = new FormData($('form').get(0));

    CallUpload(formdata);
});


function CallUpload(file) {
    console.log(file);
    $.ajax({
        url: '/api/ApiSampleUpload/Test',
        type: 'POST',
        data:  'file=' + file ,
        cache: false,
        processData: false,
        contentType: 'application/json',
        success: function () {
            alert('Success');
        },
        error: function () {
            alert('Error occured');
        }
    });
}

private static async Task TestWebAPI(string url)
{
    using (var client = new HttpClient())
    {
        using (var httpResponse = await client.GetAsync(url))
        {
            try
            {
                httpResponse.EnsureSuccessStatusCode();     //<=======EXCEPTION HERE
                string responsContent = await httpResponse.Content.ReadAsStringAsync();
            }
            catch (Exception e)
            {
                _logger.Log(LogLevel.Error, e);
            }
        }
    }
}