unity: HTTP PUT problems

I'm new to unity but I managed to do the http get, post, delete methods. My problem occurs in the PUT, I get the call right to the server, however it does not do anything, and changes everything to null, I suppose it is an error in the variable "json" but I can not fix it, if I do the put method with other tools as Postman is everything goes perfect

documentationUnityWebRequest

public void botonActualizar(){
     StartCoroutine(Upload());
}

[System.Serializable]
public class myClase
{
    public string nombre;
    public string descripcion;
}
public IEnumerator Upload()
{

    string url = "http://localhost:3001/v1/0001";
    myClase myObject = new myClase();
    myObject.nombre = "nombre";
    myObject.descripcion = "ejemplo";
    string json = JsonUtility.ToJson(myObject);

    UnityWebRequest www = UnityWebRequest.Put(url, json);
    yield return www.Send();

    if (www.isError)
    {
        Debug.Log(www.error);
    }
    else
    {
        Debug.Log("upload complete!");
    }
}