WordPress at a glance
filter is not described

woocommerce_ajax_add_order_item_validation filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_ajax_add_order_item_validation', 'filter_function_name_7875', 10, 4 );
function filter_function_name_7875( $validation_error, $product, $order, $qty ){
	// filter...

	return $validation_error;
}
$validation_error
-
$product
-
$order
-
$qty
-

Where the hook is called

WC_AJAX::maybe_add_order_item()
woocommerce_ajax_add_order_item_validation
woocommerce/includes/class-wc-ajax.php 926
$validation_error = apply_filters( 'woocommerce_ajax_add_order_item_validation', $validation_error, $product, $order, $qty );

Where in WP core the hook is used WooCommerce

Usage not found.