Order Emails not sending

I am getting following error on my log file.

[22-May-2017 18:33:37 UTC] PHP Notice: length was called incorrectly. Product properties should not be accessed directly. Backtrace: require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/Avada/page.php’), the_content, apply_filters(‘the_content’), WP_Hook->apply_filters, call_user_func_array, do_shortcode, preg_replace_callback, do_shortcode_tag, call_user_func, WC_Shortcodes::checkout, WC_Shortcodes::shortcode_wrapper, call_user_func, WC_Shortcode_Checkout::output, WC_Shortcode_Checkout::checkout, WC_Cart->calculate_totals, WC_Cart->calculate_shipping, WC_Shipping->calculate_shipping, WC_Shipping->calculate_shipping_for_package, WC_Shipping_Method->get_rates_for_package, Trs\Woocommerce\ShippingMethod->calculate_shipping, Trs\Woocommerce\Converters\PackageConverter::fromWoocommerceToCore, WC_Abstract_Legacy_Product->__get, wc_doing_it_wrong Please see Debugging in WordPress for more information. (This message was added in v in /nas/content/live/xxxxxxxxxx/wp-includes/functions.php on line 4138