wp_xmlrpc_server::error( IXR_Error|string $error, false $message = false )

Source

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

public function error( $error, $message = false ) {
		// Accepts either an error object or an error code and message
		if ( $message && ! is_object( $error ) ) {
			$error = new IXR_Error( $error, $message );
		}

		if ( ! $this->is_enabled ) {
			status_header( $error->code );
		}

		$this->output( $error->getXml() );
	}