As I need to solve this as soon as possible, I going to dig through the code (although my dev skills are limited) and posts my findings in this thread.
First finding:
If I turn on error reporting, PHP notice is returned:
Notice: Undefined variable: _error in .../libraries/julib/image.php on line 55
Does this mean, that this condition on line 18:
if(preg_match('#^(http|https|ftp)://#i', $url)) {
$headers = @get_headers($url);
if(strpos($headers[0],'200')===false) $_error = 1;
} else {
$url = JPATH_BASE .'/'. $url;
if(!file_exists($url)) $_error = 1;
}
is not returning variable $_error?