Source

File: wp-includes/class-wp-xmlrpc-server.php

protected function pingback_error( $code, $message ) {
		/**
		 * Filters the XML-RPC pingback error return.
		 *
		 * @since 3.5.1
		 *
		 * @param IXR_Error $error An IXR_Error object containing the error code and message.
		 */
		return apply_filters( 'xmlrpc_pingback_error', new IXR_Error( $code, $message ) );
	}