PHP (via IIS 7.5) is not getting post via ajax

I have an AJAX request made to the page where the AJAX routine has been defined.

Configuring the request with the POST method is not being sent. By changing to GET, it is sent successfully.

I think this might be some configuration in IIS or in PHP installation. Both are installed locally and a few days ago changes were made to them due to errors that were later discovered to be in the database, but I do not know exactly what was changed.

This is the code I'm using:

$.ajax({
    type: "POST",
    async: true,
    url: "nova_pg_novo_grupo.php?t=" + d.getTime(),
    contentType: "application/json",
    data: {
        "comando" : "salvarGrupo",
        "inputNomeGrupo" : $("#inputNomeGrupo").val()
    },
    cache: false,
    success: function(data) {
       alert(data);
        $("#divSuccess").html("Grupo salvo!");
    },
    error: function (xhr, ajaxOptions, thrownError) {
        alert(xhr.status);
        alert(thrownError);
    }
});

It was also not necessary to declare the ContentType and now does not declare Internal Server Error (500).

Edit: I think I discovered the problem, php is not displaying errors ... Thanks