src/Web/Sessions/Session.php
public function regenerateID($deleteOldSession = false)
    {
        if ($this->getIsActive()) {
            return $this->handler->regenerateId($this->id, $this->app, $deleteOldSession);
        }
        return \Reaction\Promise\reject(new Reaction\Exceptions\SessionException('Session is not active'));
    }
public function regenerateID($deleteOldSession = false)
    {
        if ($this->getIsActive()) {
            return $this->handler->regenerateId($this->id, $this->app, $deleteOldSession);
        }
        return \Reaction\Promise\reject(new Reaction\Exceptions\SessionException('Session is not active'));
    }
Updates the current session ID with a newly generated one.

Please refer to <http://php.net/session_regenerate_id> for more details.

This method has no effect when session is not [[getIsActive()|active]].
Make sure to call [[open()]] before calling it.

@param bool $deleteOldSession Whether to delete the old associated session file or not.
@see open()
@see isActive
@return \React\Promise\PromiseInterface