anchor tag link to pdf file in android firefox

Question

Executive summary: can't display a pdf file on Android Firefox.

I created an HTML page on my laptop and displayed it using Firefox. The page is a simple menu, consisting solely of links to my wife's sewing machine manuals, like so (skipping over header, title, and stuff, no css, not xhtml):

<p>&lt;ul&gt;
  <p>
    <p>&lt;li&gt;&lt;a href="file:///storage/3C5D-4F8A/Manual/thing.txt"&gt; 
     <strong>Thing
     </strong>&lt;/a&gt;&lt;/li&gt;
    </p>
    <p>&lt;li>&lt;a href="file:///storage/3C5D-4F8A/Manual/overlockbasics.pdf"&gt;
      <strong>Overlocking Basics
      </strong>&lt;/a>&lt;/li&gt;</p>
      <p>&lt;li&gt;&lt;a href="file:///storage/3C5D-4F8A/Manual/allaboutthread.pdf"&gt;
      <strong>All About Thread
      </strong>&lt;/a&gt;&lt;/li&gt;</p>
    </p>

...and so on. The goal is to have the manuals handy to the sewing machine. The phone is handy.

On a laptop, clicking the link pops up the associated pdf file, which is expected behavior. However, when I put the HTML file on her phone (and after adjusting the file paths), clicking a link returns a 'unable to download file' message.

To insure I had the correct path at least, I put that 'thing.txt' link in; clicking that returns the contents of the thing.txt file ("This is a thing", if you were wondering), so the path as specified seems correct, and that at least the text display 'plugin' works.

Tried attaching a 'type="application/pdf"' to each anchor tag, but that had no effect. From what I've discovered, Firefox is supposed to have a built-in PDF viewer - a sensible notion - although I have a suspicion that it only works with downloaded files...but if that's true, why does it work on the Win10 laptop? Inquiring minds want to know. True, there are some differences between the two platforms, so perhaps that's just the way things are.

To reiterate, the files I'm trying to display are right there on the phone's storage card.

The phone is a Galaxy S5 sport (android version 6.0.1); Firefox version is 68.3.0. The laptop is Win10, Firefox version is 71.0.

I see that other people have had problems sort of like this, but their issues appear more complex. This does not seem to be complicated, aside from the common not-working part.

If someone can suggest a solution that doesn't involve third-party add-ons, or reconfiguring Android, or dragging Google into the process, (or as someone suggested elsewhere, writing one's own browser), it's appreciated. Prefer someone pointing out what I'm doing wrong. It's entirely possible that something so simple cannot be simply done.

To see what happens on a Raspberry Pi (mainly because it was handy), I mounted the Samsung as a mts device, modified each anchor tag's path to a single dot/slash preceding the PDF file name, and ran the HTML file into both Firefox ESR, and then Chromium. Oddly, both browsers spontaneously opened and populated tiny PDF windows corresponding to each href; no link click was required. So all that demonstrated is that Firefox behaves differently depending on the platform; I'm glad you were all sitting down for that revelation. Still, it was interesting, in that those browsers had no trouble displaying something. Note I'm not complaining about that; it was just an experiment.

To recap - main interest: Firefox on the Android not displaying PDF when anchor tag clicked.

Thanks.