What potential server-side permission issues could lead to a "Forbidden" error message in a PHP registration form?

The "Forbidden" error message in a PHP registration form could be caused by incorrect file permissions on the server-side script handling the form submission. To solve this issue, you need to ensure that the script file has the appropriate permissions set to allow it to be executed by the web server.

// Set the correct permissions for the PHP registration form script
chmod("registration_form.php", 0644);