Pasted

/**
 * Prohibit a product category
 */
function custom_add_validation_rules_category() {
 
    if ( ! isset( WC()->cart ) ) {
        return;
    }
 
    $shipping_country      = WC()->customer->get_shipping_country();
    $shipping_state        = WC()->customer->get_shipping_state();
    $cart_contents         = WC()->cart->cart_contents;
    $cart_product_ids      = wp_list_pluck( $cart_contents, 'product_id' );
    $prohibited_categories = array( 34 ); // Add prohibited category IDs
 
    // Loop through each product to check if anyone has any prohitibited category
    foreach ( $cart_product_ids as $product_id ) {
        if ( array_intersect( wp_get_post_terms( $product_id, 'product_cat', array( 'fields' => 'ids' ) ), $prohibited_categories ) ) {
            wc_add_notice( __( 'There are some product (categories) in your cart that cannot be shipped to your location.' ), 'error' );
            break;
        }
    }
 
}
add_action( 'woocommerce_checkout_process', 'custom_add_validation_rules_category' );