Error message

An error message is come up in my sidebar as :

Warning: Attempt to assign property of non-object in /home/a3463815/public_html/wp-includes/rss.php on line 440

Web site: http://sri.890m.com

Please tell me a solution to remove this.
I’m going to upgrade the latest version of wordpress manually.
But I want resolve the problem before.
Hopes you can help me.
Thank you very much.

http://sri.890m.com/