I keep getting the below error while editing the front

Hi,

I keep getting the below error while editing the front page. Could you help me as to why? Thanks.

Warning: DOMDocument::loadHTML(): Invalid char in CDATA 0x3 in Entity, line: 2 in /home/www/wp.hyst.dk/wp-content/themes/upfront/elements/upfront-text/lib/upfront_text.php on line 21