Fatal error: Uncaught Error: Call to undefined method WooCommerce::add_error() in /home/elmercad/public_html/wp-content/plugins/woocommerce-measurement-price-calculator/classes/class-wc-price-calculator-cart.php:114 Stack trace: #0 /home/elmercad/public_html/wp-includes/class-wp-hook.php(286): WC_Price_Calculator_Cart->add_to_cart_validation(true, 601, 1) #1 /home/elmercad/public_html/wp-includes/plugin.php(203): WP_Hook->apply_filters(true, Array) #2 /home/elmercad/public_html/wp-content/plugins/woocommerce/includes/class-wc-form-handler.php(753): apply_filters('woocommerce_add...', true, 601, 1) #3 /home/elmercad/public_html/wp-content/plugins/woocommerce/includes/class-wc-form-handler.php(729): WC_Form_Handler::add_to_cart_handler_simple(601) #4 /home/elmercad/public_html/wp-includes/class-wp-hook.php(286): WC_Form_Handler::add_to_cart_action('') #5 /home/elmercad/public_html/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array) #6 /home/elmercad/public_html/wp-includes/plugin.php(453): WP_Hook->do_ac in /home/elmercad/public_html/wp-content/plugins/woocommerce-measurement-price-calculator/classes/class-wc-price-calculator-cart.php on line 114