How do I get around this error in my .net application

Question

This is my error

SocketException: No connection could be made because the target machine actively refused it.

I am getting it on this code

public class AppService : IAppService
{
    public async Task<MainResponse> AuthenticateUser(LoginModel loginModel)
    {
        var returnResponse = new MainResponse();

        using (var client = new HttpClient())
        {
            var url = $"{Setting.BaseUrl}{UserAPIs.AuthenticateUser}";

            var serializedStr = JsonConvert.SerializeObject(loginModel);

            var response = await client.PostAsync(url, new StringContent(serializedStr, Encoding.UTF8, "application/json"));

            if (response.IsSuccessStatusCode)
            {
                string contentStr = await response.Content.ReadAsStringAsync();
                returnResponse = JsonConvert.DeserializeObject<MainResponse>(contentStr);
            }
        }

        return returnResponse;
    }
}

This is my controller code for the API All of my port numbers are right and all other API's are running correctly I just cant get passed the log in with the username and password

    [AllowAnonymous]
    [HttpPost("AuthenticateUser")]
    public async Task<IActionResult> AuthenticateUser(LoginModel authenticateUser)
    {
        try
        {
            var user = await _userManager.FindByNameAsync(authenticateUser.UserName);
            if (user == null) return Unauthorized();

            bool isValidUser = await _userManager.CheckPasswordAsync(user, authenticateUser.Password);

            if (isValidUser)
            {
                string accessToken = GenerateAccessToken(user);
                var refreshToken = GenerateRefreshToken();
                await _userManager.UpdateAsync(user);

                var role = await _userManager.GetRolesAsync(user);

                int? roleID = null;
                switch (role?.FirstOrDefault())
                {
                    case "Admin":
                        roleID = (int)RoleEnum.Admin;
                        break;
                    case "Student":
                        roleID = (int)RoleEnum.Student;
                        break;
                    case "Teacher":
                        roleID = (int)RoleEnum.Teacher;
                        break;
                }

                var response = new MainResponse
                {
                    Content = new AuthenticationResponse
                    {
                        RefreshToken = refreshToken,
                        AccessToken = accessToken,
                        RoleID = roleID
                    },
                    IsSuccess = true,
                    ErrorMessage = ""
                };
                return Ok(response);
            }

            else
            {
                return Unauthorized();
            }
        }
        catch (Exception ex)
        {
            var response = new MainResponse
            {
                Content = new AuthenticationResponse
                {
                    RefreshToken = null,
                    AccessToken = null,
                    RoleID = null,
                    DeviceToken = null
                },
                IsSuccess = true,
                ErrorMessage = ex.Message
            };
            return Ok(response);
        }
    }

Answer 1

Try these..

1. Make sure the API is Up.

2. Check the URL

3. Add exception handling in your code

   public async Task AuthenticateUser(LoginModel loginModel) { var returnResponse = new MainResponse();

   try
   {
       using (var client = new HttpClient())
       {
           var url = $"{Setting.BaseUrl}{UserAPIs.AuthenticateUser}";
   
           var serializedStr = JsonConvert.SerializeObject(loginModel);
   
           var response = await client.PostAsync(url, new StringContent(serializedStr, Encoding.UTF8, "application/json"));
   
           if (response.IsSuccessStatusCode)
           {
               string contentStr = await response.Content.ReadAsStringAsync();
               returnResponse = JsonConvert.DeserializeObject<MainResponse>(contentStr);
           }
       }
   }
   catch (Exception ex)
   {
       // Log or display the exception details for troubleshooting.
       Console.WriteLine($"Error: {ex.Message}");
       // You can also throw the exception if needed.
       // throw;
   }
   
   return returnResponse;
   

   }