First info:
Updated libraries: We updated jquery, backbone, and a couple other libraries. This may cause your browsers to render oddly. Please remember to flush your cache (browser and website/server). If you’re using Cloudflare, you may need to kick it.

As an example:
Change this:
$( ‘a[href*=#]:not([href=#])’ ).click( function() {
To this:
$( ‘a[href*=”#”]:not([href=”#”])’ ).click( function() {

Adding this in functions.php should work according to my sources (BUT REMOVE THIS WHEN THE PROBLEM IS FIXED !):
if (!is_admin()) {
wp_deregister_script(‘jquery’);
wp_register_script(‘jquery’, (“http://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js”), false, ‘1.11.3’);
wp_enqueue_script(‘jquery’);
}