What Should I do I am getting Fatal Error from this code?

Question

Getting this error:-

Fatal error: Uncaught PDOException: SQLSTATE[HY000] [1045] Access denied for user 'root'@'localhost' (using password: NO) in C:\WEB-PROJECT\xampp\htdocs\facebook\core\database\connection.php:8 Stack trace: #0 C:\WEB-PROJECT\xampp\htdocs\facebook\core\database\connection.php(8): PDO->__construct('mysql:host=127....', 'root', '') #1 C:\WEB-PROJECT\xampp\htdocs\facebook\core\load.php(3): include('C:\WEB-PROJECT\...') #2 C:\WEB-PROJECT\xampp\htdocs\facebook\sign.php(4): require('C:\WEB-PROJECT\...') #3 {main} thrown in C:\WEB-PROJECT\xampp\htdocs\facebook\core\database\connection.php on line 8

From this code:- <?php

$hostDetails = 'mysql:host=127.0.0.1; dbname=facebook; charset=utf8mb4';
$userAdmin = 'root';
$pass = '';

try{
    $pdo = new PDO($hostDetails,$userAdmin,$pass);
} catch(PDOExecption $e){
    echo 'Connection error!' . $e->getMessage();
}

?>