I have found a bug after the upgrading the Wordpress to the last version of the software 3.9.

I get this error:

> 
> Thu Apr 17 17:21:52 2014] [warn] mod\_fcgid: stderr: PHP Catchable
>  fatal error: Object of class WP\_Post could not be converted to string
>  in /wp-content/plugins/qtranslate/qtranslate\_core.php on line 455,
>  referer: <http://www.mywebsite.com/>
> 
> 
> 

Why do this happen?