I also have the 403 error and I found a solution in the following url : https://wordpress.org/support/topic/wc-ajaxupdate_order_review-403-error/
When I add this code in wp-config.php , the ?wc-ajax=update_order_review (403) error is gone and the spinner disappear in the checkout page.
define( ‘ADMIN_COOKIE_PATH’, ‘/’ ); define( ‘COOKIE_DOMAIN’, ” ); define( ‘COOKIEPATH’, ” ); define( ‘SITECOOKIEPATH’, ” );
I don’t understand how it works but it solved my problem.
