class.xt_fileupload.php line 460

public function get_uploaded_filename(string $field_name, string $subfield =
null)
    {
        $file = $this->get_file_record( $field_name, $subfield );
        if( !$file ) return;
        // return $this->get_new_filename( $field_name );   // generates error
        return $this->get_new_filename( $file['name'] );
    }


found bug in CGE when using products to add new item & upload image on first
save
details: http://dev.cmsmadesimple.org/bug/view/12385 

Not sure where else this method is used, but tested this fix with Products & CGE