[25-Jun-2019 03:14:24 America/Los_Angeles] PHP Fatal error:  Uncaught Error: Call to a member function bindParam() on boolean in /ruta/ipn.php:79
Stack trace:
#0 {main}
  thrown in /ruta/ipn.php on line 79

$sentencia = $conn->prepare("INSERT INTO invoices (id_ass, invoiceid, packageid, paypalemail) VALUES (:id_ass, :invoiceid, :packageid, :paypalemail)");
        $sentencia->bindParam(':id_ass', $id);
        $sentencia->bindParam(':invoiceid', $_POST['txn_id']);
        $sentencia->bindParam(':packageid', $packageid);
        $sentencia->bindParam(':paypalemail', $_POST['payer_email']);
        $sentencia->execute();

$sentencia = $conn->prepare("INSERT INTO invoices (id_ass, invoiceid, packageid, paypalemail) VALUES (?, ?, ?, ?)");
$sentencia->bind_param('iiis', $id, $_POST['txn_id'], $packageid, $_POST['payer_email']);
$sentencia->execute();

$sentencia = $conn->prepare("INSERT INTO invoices (id_ass, invoiceid, packageid, paypalemail) VALUES (?,?,?,?)");
 $stmt->bind_param('ssss', $id, $_POST['txn_id'], $packageid, $_POST['payer_email']);
 $stmt-excute();