Error "DataTable warning: table id = tableID - Ajax error"

I'm working with DataTable and Ajax, I have an error that says:

  

DataTable warning: table id = tableID - Ajax error. For more information about this error

I do not print the data in PHP, I do not return anything, I want to clarify that this only happens to me with other computers, in which I'm working, everything is fine, if you return the data. The way I return the data from PHP is as follows:

$dataa = array();
$query = "select * from tabla";
$consulta = $obj->query($query);

while ($response = $obj->fetch_array($consulta))
    {
    $fila = array_map('utf8_encode', $response);
    $datos['c1'] = $fila['campo1'];
    $datos['c2'] = $fila['campo2'];
    array_push($dataa, $datos);
    }

echo '{"aaData":' . json_encode($dataa) . '}';