I'm scraping pdf files from a site using Scrapy, a Python web-scraping framework.
The site requires to follow the same session in order to allow you to download the pdf. 
It works great with Scrapy's because it's all automated but when I run the script after a couple of seconds it starts to give me fake pdf files like when I try to access directly the pdf, without my session.
Why is that so & any idea how to overcome this problem!?
I think the site tracks your session. If it's a PHP site, pass PHPSESSID cookie to the request which downloads the PDF file.
Downloading PDF files with Scrapy