Data pass using POST method - WebRequest object

I want to use POST method to pass data over web server. I want to retrieve data provided by web server in JSON format. I have used following code by referring Unity Manual.

    void Start ()
		StartCoroutine (LoadLoginInfo ());

	IEnumerator LoadLoginInfo ()
		Debug.Log("Load Login Info");

		WWWForm form = new WWWForm ();
		form.AddField ("username", "admin");
		form.AddField ("password", "Admin123#");

		UnityWebRequest www = UnityWebRequest.Post (url, form);
		yield return www.Send();

		if (www.isError) {
			Debug.Log (www.error);
		} else {
			Debug.Log ("Login Data Retrieved");

But after certain amount of wait, I am getting following message in console.


I have already checked this thing into browser but at their everything working normal.

So what is the correct way to use POST method using WebRequest object?

Add Debug.Log(request.downloadHandler.text);
See code below

void Start()

IEnumerator Post()
	WWWForm wwwf = new WWWForm ();
	wwwf.AddField("object_or_array", "object");
	wwwf.AddField("empty", "false");
	wwwf.AddField("parse_time_nanoseconds", "78983");
	wwwf.AddField("validate", "true");
	wwwf.AddField("size", "1");

	var request = UnityWebRequest.Post("", wwwf);

	yield return request.Send();


response output
“object_or_array”: “object”,
“empty”: false,
“parse_time_nanoseconds”: 46600,
“validate”: true,
“size”: 1