ASP.Net Core HttpClient from Console returns 503 "Service Unavailable"

Question

Problem: HttpClient returns 503 "Service Unavailable" when accessing locally hosted API through console app while it can be accessed successfully using Edge. Am I missing some configurations?

Code:

using System;
using System.Net.Http;
using System.Threading.Tasks;

namespace SampleClient
{
    public class Program
    {
        private static HttpClient Client = new HttpClient();
        public static async Task Main(string[] args) 
        {
            Console.WriteLine("Starting connections");
            for(int i = 0; i<5; i++)
            {

                var result = await Client.GetAsync("http://localhost:5100/api/contacts");
                //var result = await Client.GetAsync("https://stackoverflow.com/");
                Console.WriteLine(result.StatusCode);
            }
            Console.WriteLine("Connections done");
        }
    }
}

--- build ---

dotnet build

...

Build succeeded. 0 Warning(s) 0 Error(s)

sample output: screenshot

clear headers

in your api side, please enable debug level log and check if there is any error in log — Elendil Zheng-MSFT
What about if you try add Client.DefaultRequestHeaders.Accept.Clear(); Client.DefaultRequestHeaders.Accept.Add( new MediaTypeWithQualityHeaderValue("application/json")); before you calling GetAsync? — Selim Yildiz
@ElendilZheng-MSFT I think API is working properly. As shown in the screenshots, it can be displayed in Edge. (even in firefox, chrome and postman) — McKoy
Did you start your .net core hosted instance or IIS website/apppool prior to executing the Get to localhost:5100? — Stinky Towel

McKoy McKoy · Accepted Answer · 2020-03-07T05:42:13

Sorry. The cause is the Antivirus firewall. After disabling, I was able to access successfully.

ASP.Net Core HttpClient from Console returns 503 "Service Unavailable"

1 Answers