Fatal error: Uncaught TypeError: mysqli_fetch_object()

Kesalahan Detail :

Fatal error: Uncaught TypeError: mysqli_fetch_object(): Argument #1 ($result) must be of type mysqli_result, bool given in C:\xampp\htdocs\psb\index.php:8 Stack trace: #0 C:\xampp\htdocs\psb\index.php(8): mysqli_fetch_object(false) #1 {main} thrown in C:\xampp\htdocs\psb\index.php on line 8

Code Line 8

$d = mysqli_fetch_object($getMaxId);

Full Code

<?php
include 'konek.php';

if (isset($_POST['submit'])) {

    // ambil 1 id terbesar di kolom id_pendaftaran, lalu ambil 5 karakter aja dari sebelah kanan
    $getMaxId = mysqli_query($con, "SELECT MAX(RIGHT(id_pendaftaran, 5)) AS id FROM tb_pendaftaran");
    $d = mysqli_fetch_object($getMaxId);
    $generateId = 'P' . date('Y') . sprintf("%05s", $d->id + 1);
    echo $generateId;
}
?>