While you have your FTP connected to your Web hosting server, make sure the following PrestaShop folders have ‘write’ permissions (also known as “CHMOD 755”) but do not apply these permissions recursively (to their subfolders): /config, /upload, /download, /tools/smarty/compile. Then make sure the following folders have ‘write’ permissions and apply these permissions recursively (to their subfolders): /img, /mails, /modules, /themes/prestashop/lang, /translations