Some Pdfs shared by a link are not readble



I would like to share some strange behaviour from OC 8.1.3.
OC is running on a shared host, simple Webinstall with HSTS.
The encrypted filesystem is choosen

We can upload files without Problems.
However when we share PDF's with a link certain files cannot be read.
These were re-shared without effect, the user that made the link is an administrator.

does anyone had somethong similar?
If I should update to what version and can it be done by overwriting the php-files with an upload?

I would be greatfull for any hint in the right direction.



From the template shown when creating a new thread:

make sure that you're running the latest available version for your oC release:



the updates have been made we are now running 8.2.7.

PDFs and also ODT load in an iFrame and my guess is that Firefox, but also some other OS-Browser combinations forbid to load the images (IE 11 on Win8.1 shows them).

Does anyone have an idea what to "open up" in order to see the images?

I am searching all kind of fora to see what I can find.