Using 4.2.2. here – I’m also having this issue with PDFs. I can upload them into the media library but when I try to access their URLs – both from my end in the Dashboard and from the user’s end on the site – I get an internal server error.
My initial digging into this issue led me to a thread that called it a PhP issue, and that I had to upgrade to PhP 5.5. I’m hosted by FatCow which only lets me upgrade to 5.3, but after I did so with FatCow I’m still having problems. I’ve tried uploading the PDFs through an FTP client and the problem remains.
Oh – and I should also add that this ONLY applies to PDFs that I’ve recently tried to upload. Everything from before about a month ago loads just fine.
Any insight – anyone?