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WooCommerce: show checkout error if weight exceeds a threshold
A WooCommerce fan asked me: “How do you deny checkout if the cart weight is above a certain threshold?“.
Well, this is straight forward thanks to a WooCommerce core function called “cart_contents_weight” which allows you to get the total weight of your cart, and then the “wc_add_notice” function which shows a notification error.
Enjoy!

PHP Snippet: Deny WooCommerce Checkout Processing if Cart Weight > Threshold
/**
* @snippet Deny Checkout Based on Cart Weight - WooCommerce
* @how-to Get tutoraspire.com FREE
* @author Tutor Aspire
* @compatible WooCommerce 6
* @donate $9 https://www.tutoraspire.com
*/
add_action( 'woocommerce_after_checkout_validation', 'tutoraspire_deny_checkout_if_weight' );
function tutoraspire_deny_checkout_if_weight( $posted ) {
$max_weight = 100;
if ( WC()->cart->cart_contents_weight > $max_weight ) {
$notice = 'Sorry, your cart has exceeded the maximum allowed weight of ' . $max_weight . get_option( 'woocommerce_weight_unit' );
wc_add_notice( $notice, 'error' );
}
}