Have the same problem:
Fatal error: Uncaught Error: Call to undefined function wc_pdf_product_vouchers_render_product_voucher_fields() in /home/wp-content/plugins/woocommerce-pdf-product-vouchers/includes/class-wc-pdf-product-vouchers-product.php:60 Stack trace: #0 /home/wp-includes/class-wp-hook.php(287): WC_PDF_Product_Vouchers_Product->render_product_voucher_options(”) #1 /home/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(”, Array) #2 /home/wp-includes/plugin.php(484): WP_Hook->do_action(Array) #3 /home/wp-content/plugins/woocommerce/templates/single-product/add-to-cart/simple.php(33): do_action(‘woocommerce_bef…’) #4 /home/wp-content/plugins/woocommerce/includes/wc-core-functions.php(345): include(‘/home/…’) #5 /home/wp-content/plugins/woocommerce/includes/wc-template-functions.php(1625): wc_get_template(‘single-product/…’) #6 /home/wp-includes/class-wp-hook.ph in /home/wp-content/plugins/woocommerce-pdf-product-vouchers/includes/class-wc-pdf-product-vouchers-product.php on line 60
If woocommerce voucher is deactivated, the error desapears…
