I am not sure if my version of Firefox Quantum is set to update automatically, but all of a sudden the other day a few of my bookmarks (URLs that previously displayed PDFs) stopped displaying PDFs in my Firefox Quantum browser. One URL that I had viewed in my browser everyday (a gym timetable) now automatically downloads the PDF rather than display it in the browser (which is annoying because 1) I have to navigate to my downloads to open the file instead of it being displayed instantly and 2) I have to delete the PDF every time I view it (it is changing constantly so that's why I want to open the PDF in the browser without the hassle of the download). I assumed it was a change that the website manager had made, so I initially asked that question but have not yet received a response. But now I am experiencing problems opening other PDFs - in some cases they won't open OR download at all! I followed one piece of forum advice which was to disable all extensions and then test to see if that fixed the problem. Unfortunately it did not. Then just now I have updated to the latest version: Firefox Quantum 66.0.2 (64-bit) thinking that that action might solve the problem. But it did not. I would be so grateful if anyone could shed some light on this. It is most frustrating. I have tried opening the PDFs in Chrome, for example, and they seem to display fine and as normal inside the Chrome browser window. But I want to use Firefox! Help!