Fatal error: Uncaught Error: Class "FPDF" not found in /home/xstore/public_html/wp-content/plugins/yith-woocommerce-pdf-invoice-premium/lib/vendor/setasign/fpdi/src/FpdfTpl.php:19 Stack trace: #0 {main} thrown in /home/xstore/public_html/wp-content/plugins/yith-woocommerce-pdf-invoice-premium/lib/vendor/setasign/fpdi/src/FpdfTpl.php on line 19