Fatal error: Class ‘DOMDocument’ not found

Hi There, we are having an issue, that woocommerce is not generating the HTML template properly and also causing no invoice to be attached to the emails. Can you please offer any assistance?

Fatal error: Class 'DOMDocument' not found

#0 /home/XYZ/public_html/XYZ/wp-content/plugins/woocommerce-pdf-invoices-packing-slips/includes/class-wcpdf-pdf-maker.php(51): Dompdf\Dompdf->loadHtml('...')
#1 /home/XYZ/public_html/XYZ/wp-content/plugins/woocommerce-pdf-invoices-packing-slips/includes/documents/abstract-wcpdf-order-document.php(741): WPO\WC\PDF_Invoices\PDF_Maker->output()
#2 /home/XYZ/public_html/XYZ/wp-content/plugins/woocommerce-pdf-invoices-packing-slips/includes/documents/abstract-wcpdf-order-document.php(776): WPO\WC\PDF_Invoices\Documents\Order_Document->get_pdf()
#3 /home/XYZ/public_html/XYZ/wp-content/plugins/woocommerce-pdf-invoices-packing-slips/includes/class-wcpdf-main.php(373): WPO\WC\PDF_Invoices\Documents\Order_Document->output_pdf('inline')
#4 /home/XYZ/public_html/XYZ/wp-includes/class-wp-hook.php(303): WPO\WC\PDF_Invoices\Main->generate_pdf_ajax('')
#5 /home/XYZ/public_html/XYZ/wp-includes/class-wp-hook.php(327): WP_Hook->apply_filters('', Array)
#6 /home/XYZ/public_html/XYZ/wp-includes/plugin.php(470): WP_Hook->do_action(Array)
#7 /home/XYZ/public_html/XYZ/wp-admin/admin-ajax.php(187): do_action('wp_ajax_generat...')
#8 {main}

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