Hi @010oussama,
Are you password protecting your admin area via .htaccess? If so, you need to allow access to admin-ajax.php so all public AJAX calls are executed correctly.
See here for more: How to password protect your WordPress Admin (wp-admin) directory.
No this problem appears in every page in my website such as the contact us page!
I know. Please read again: there’s a password protection set that prevents access to your wp-admin folder. So it happens that in this folder is located the admin-ajax.php file which themes and plugins use to execute AJAX calls (including WPP of course).
So, you either manually password protected your wp-admin area or you’re using a security plugin that provides this feature. The solution is what I posted on my previous reply.
