Website Forum: Attached files are not found

I am looking at this thread in the Trisquel Forum: https://trisquel.info/gl/forum/problema-con-icecat-en-trisquel-11 The first message has an attached file. When I click on the link to open the file, I get a "Page not found" page.

However, in the synchronized e-mail list, the image arrives just fine, attached to the message.