访问被拒绝用户'root'@'localhost'（使用密码：否）[复制]

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I have an ecommerce website and i m trying to move from localhost windows to linux mint localhost.. I can log in to phpmyadmin , so i know the root and the password, i changed the config.inc.php and AllowNoPassword = True but when i try localhost/ecommerce i get access denied and Using PAssword (NO)..

$db = mysqli_connect('localhost', 'root', 'admin', 'ecommerce');
    if(mysqli_connect_errno()) {
        echo 'Database connection failed with following errors: '.mysqli_connect_error();
        die();

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