Firefox is a Web browser. Yes, you can access files from it, but it's not a File browser. See screenshot

Chrome does the same thing. see screenshot

I had that problem with local pdf files which was a deliberate change with FF91. I don't know why you would be having the issue with files on websites. You can prevent it by disabling Firefox as a pdf viewer. In a new tab enter about:config, accept the risk and make the following preference true. pdfjs.disabled

Perfect, many thanks!

The only downside of this fix is that I now cannot use the FF pdf viewer at all. If I select FF from the "always ask" dialog, I get stuck in a loop, it just repeatedly brings up the "always ask" dialog until I select a different viewer. But I can live without the FF viewer...

If any FF peeps see this, would really appreciate a proper fix

Firefox is a Web browser. Yes, you can access files from it, but it's not a File browser. See screenshot

Not sure what your point is. The "Web" doesn't exclude local networks

I'm sure we are not the only company on the planet that uses an internal wiki, with links to files on our internal network. Over the years FF has made this more and more difficult...

It's a deliberate change and it won't be undone: https://bugzilla.mozilla.org/show_bug.cgi?id=1733362

It's a deliberate change and it won't be undone: https://bugzilla.mozilla.org/show_bug.cgi?id=1733362

Thanks, well spotted

So its a bug that they don't appreciate the significance of. As :Gijs says "I have to confess I'm struggling to understand the usecase here for the behaviour you want. "Downloading" a file that is already stored on file:/// is not really a useful thing to do."

Similar to Hartmut's reply on that thread, we use internal wikis for documenting our work (electronic design, hardware and software), and these wikis are littered with references to local pdfs (e.g. datasheets, specs, project plans etc). It is waaaay easier to just click a link, rather than manually navigate our local filing systems to find each pdf.