Reply To: Logfile: The "add_to_cart_fragments" hook uses out of date data structure
There is an additional warning which looks similar:
The “woocommerce_add_order_item_meta” hook uses out of date data structures and function is deprecated since version 3.1.2. Replace with woocommerce_new_order_item., referer: https://otesys.com/kasse?woo-paypal-return=true&
Note: I deleted the token= and Payer-ID= from the end of the line
The reason for me looking in my logfile was an email informtion from PayPal, that payment confirmations could not be sent to my server. Maybe it is related to this.