A configuration issue prevents <acronym title="Content Delivery Network">CDN</acronym> from working:\n                                            The <strong>"Replace default hostname with"</strong>\n                                            field cannot be empty. Enter <acronym\n                                            title="Content Delivery Network">CDN</acronym>\n                                            provider hostname <a href="?page=w3tc_cdn#configuration">here</a>.\n                                            <em>(This is the hostname used in order to view objects\n                                            in a browser.)</em>