File not Found error Downloading PDF

[BluAlien]

I upgraded mw from 1.17 to 1.19.1 and Collection Extension from 1.5 to 1.6.1, my PHP Version is 5.3.6 (ubuntu). Before the upgrade all was ok, but now it stop working. The system renders correctly the document, but when I try to download the pdf I got the File Not Found message and in the mwlibcahce dir I can found the file output.rl that if renamed in .pdf is exactly the pdf version of my document. I'm became crazy, is somone that can suggest a solution ?

Thanks in advance.

[BluAlien]

SOLVED !!! 

I used mwlib 0.12 on mw 1.17. Upgraded to 0.14 and all went ok !