Fatal error: Uncaught Error: Call to undefined function add_filter() in /home/propicalestates/public_html/wp-content-keep it /plugins/leaky-paywall/include/gateways/paypal/functions.php:34 Stack trace: #0 {main} thrown in /home/propicalestates/public_html/wp-content-keep it /plugins/leaky-paywall/include/gateways/paypal/functions.php on line 34