User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:82.0) Gecko/20100101 Firefox/82.0

Steps to reproduce:

Open a pdf: https://w3.org/wai/er/tests/xhtml/testfiles/resources/pdf/dummy.pdf

Actual results:

Save dialog was opened

Expected results:

The pdf should have been loaded in the browser (pdf.js)

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

It seems to be related to this bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1661777 but not sure what the reasoning was behind this. It makes browsing quite difficult.

You'll want to reset your PDF viewer settings, Preferences->Applications->Portable Document Format (PDF) to "Open in Firefox (or Nightly/Beta)"

(In reply to Brendan Dahl [:bdahl] from comment #4)

You'll want to reset your PDF viewer settings, Preferences->Applications->Portable Document Format (PDF) to "Open in Firefox (or Nightly/Beta)"

*** This bug has been marked as a duplicate of bug 1660277 ***

Thanks, this did work, although this is rather un-intuitive, as I certainly never changed that setting before. I know I got the option it in the Save dialog, but it's not very clear that that's what it does (as opposed to Downloading it, then opening it, which is what I thought that option did).

Just commenting because many other people might run into this.

You probably didn't change the setting but it was a bug that caused the change. Note that this may happen again until bug 1660277 is fixed.