If you are receiving PHP/MySQL authentication issues, and errors such as the following:
PHP Warning: PDO::__construct(): The server requested authentication method unknown to the client [mysql_old_password]
You may need to reset your MySQL user password in order to update the old password hash associated with the account. This is because older versions of MySQL stored passwords using a different (and less secure) method than later versions. To change your MySQL password, please do the following;
1. Obtain your old password.
You can usually find your current database password within your website configuration files. For Wordpress, this is the wp-config.php file of your website. Locate your password and copy it to your clipboard for convenience later.
2. Login to cPanel.
3. Select "MySQL Databases" under the "Databases" section:
4. Scroll to the bottom of this page, and locate the MySQL user you wish to change the password for and click the "Change Password" link:
5. Re-enter or enter a new database password for the user. We strongly recommend choosing a very secure password to maintain good security. If you want to generate a new password, we recommend using the generation tool provided. When you're ready, click the 'Change Password' button:
6. If you generated a new password above, you now need to update your website file(s) to use this new password. If you are using Wordpress, this password will need to be changed in your wp-config.php file. Any other software is beyond the scope of this support article, and you will need to contact the appropriate software developers if you require assistance. If you do not update your site files with this new password, you will continue to experience error messages.