Comment 15 for bug 1447107

Eventum versión : 2.3.3, that's old!
try Eventum 3.0.1 then!

as i can see 2.3.3 has different code:
https://github.com/eventum/eventum/blob/release-2.3.3-final/lib/eventum/class.attachment.php#L60-L88

you could just try replacing whole function body, no warranties!