This happened to me too, deactivated the plugin until further notice.
EDIT: Cleared my cache and reactivated it and now i am getting these errors with my woocommerce-wishlist in addition to the ones mentioned above…
Warning: session_start() [function.session-start]: Cannot send session cache limiter – headers already sent (output started at …wp-content/plugins/aftership-woocommerce-tracking/aftership.php:117) in …wp-content/plugins/yith-woocommerce-wishlist/class.yith-wcwl.php on line 54
Warning: Cannot modify header information – headers already sent by (output started at …wp-content/plugins/aftership-woocommerce-tracking/aftership.php:117) in …wp-content/plugins/yith-woocommerce-wishlist/functions.yith-wcwl.php on line 118
