RSGallery2
RSGallery2 1.13.2 - Cannot delete gallery via backend
I got this issue as well. The problem is in gallery.class.php file which doens't check if the function is available when trying to generate var $this->url (line 304).
I think guys should use if( function_exists( 'sefRelToAbs' ) ) notation like they do later in 315 line of that file.
I workarounded this issue replacing line 304
$this->url = sefRelToAbs("index.php?option=com_rsgallery2&Itemid=$Itemid&catid=".$this->get('id'));with this one
$this->url = "index.php?option=com_rsgallery2&Itemid=$Itemid&catid=".$this->get('id');