woocommerce_after_checkout_validation action-hookWC 1.0

Usage

add_action( 'woocommerce_after_checkout_validation', 'wp_kama_woocommerce_after_checkout_validation_action', 10, 2 );

/**
 * Function for `woocommerce_after_checkout_validation` action-hook.
 * 
 * @param  $data   
 * @param  $errors 
 *
 * @return void
 */
function wp_kama_woocommerce_after_checkout_validation_action( $data, $errors ){

	// action...
}
$data
-
$errors
-

Where the hook is called

WC_Checkout::validate_checkout()
woocommerce_after_checkout_validation
woocommerce/includes/class-wc-checkout.php 889
do_action( 'woocommerce_after_checkout_validation', $data, $errors );

Where the hook is used in WooCommerce

woocommerce/includes/class-wc-cart.php 112
add_action( 'woocommerce_after_checkout_validation', array( $this, 'check_customer_coupons' ), 1, 2 );