LluĂs wrote:
In the web page here:
https://www.torproject.org/download/download.html.en#warning
advises us not to "... open documents downloaded through Tor while online"
Many technical manuals and scientific papers are written in pdf format, and I usually read them.
Also, if you use the in-built PDF reader in Tor Browser then you should be safe. But not all PDF downloads use the correct PDF MIME type, which is why your browser might want to download it and show that particular error.