Fatal error: Uncaught Error: Interface "PayPal\Handler\IPayPalHandler" not found in /home/custom/public_html/katiekarr/vendor/paypal/rest-api-sdk-php/lib/PayPal/Handler/OauthHandler.php:18 Stack trace: #0 {main} thrown in /home/custom/public_html/katiekarr/vendor/paypal/rest-api-sdk-php/lib/PayPal/Handler/OauthHandler.php on line 18