I'm running Firefox 113.0.2 on Linux but of recent it does not show
content of pdf's.
Is this a local problem or does it happen to others?

Dirk T. Verbeek <dirk@example.com> wrote:

>I'm running Firefox 113.0.2 on Linux but of recent it does not show
>content of pdf's.
>Is this a local problem or does it happen to others?

I'm running that version on Linux Mint. I just changed the setting in
about:preferences > General > Applications to "Open in Firefox". I was
able to open a pdf from the Web in Firefox. Normally I save pdfs locally
and open outside Firefox.

On 5/26/23 11:25, this is what Adam H. Kerman wrote:
> Dirk T. Verbeek <dirk@example.com> wrote:
>
>> I'm running Firefox 113.0.2 on Linux but of recent it does not show
>> content of pdf's.
>> Is this a local problem or does it happen to others?
>
> I'm running that version on Linux Mint. I just changed the setting in
> about:preferences > General > Applications to "Open in Firefox". I was
> able to open a pdf from the Web in Firefox. Normally I save pdfs locally
> and open outside Firefox.
I selected a pdf from my "documents" folder and had to do an "open with" to get FF to view it, but it did, and
multi-pages at that.
--
Linux Mint 21.1 Cinnamon 5.6.8
Al

Op 26-05-2023 om 18:00 schreef Big Al:
> On 5/26/23 11:25, this is what Adam H. Kerman wrote:
>> Dirk T. Verbeek <dirk@example.com> wrote:
>>
>>> I'm running Firefox 113.0.2 on Linux but of recent it does not show
>>> content of pdf's.
>>> Is this a local problem or does it happen to others?
>>
>> I'm running that version on Linux Mint. I just changed the setting in
>> about:preferences > General > Applications to "Open in Firefox". I was
>> able to open a pdf from the Web in Firefox. Normally I save pdfs locally
>> and open outside Firefox.
> I selected a pdf from my "documents" folder and had to do an "open with"
> to get FF to view it, but it did, and multi-pages at that.
Good point, I just did the same and it opens.

What does not work for me is opening a pdf via the Outlook (company) web
mail.
Ah well, there are plenty of other pdf readers to chose from.

On 5/26/23 13:16, this is what Dirk T. Verbeek wrote:
> Op 26-05-2023 om 18:00 schreef Big Al:
>> On 5/26/23 11:25, this is what Adam H. Kerman wrote:
>>> Dirk T. Verbeek <dirk@example.com> wrote:
>>>
>>>> I'm running Firefox 113.0.2 on Linux but of recent it does not show
>>>> content of pdf's.
>>>> Is this a local problem or does it happen to others?
>>>
>>> I'm running that version on Linux Mint. I just changed the setting in
>>> about:preferences > General > Applications to "Open in Firefox". I was
>>> able to open a pdf from the Web in Firefox. Normally I save pdfs locally
>>> and open outside Firefox.
>> I selected a pdf from my "documents" folder and had to do an "open with" to get FF to view it, but it did, and
>> multi-pages at that.
> Good point, I just did the same and it opens.
>
> What does not work for me is opening a pdf via the Outlook (company) web mail.
> Ah well, there are plenty of other pdf readers to chose from.
I've got pdf's to open in xreader. I comes up way way faster than firefox, and it's built in.
--
Linux Mint 21.1 Cinnamon 5.6.8
Al

"Dirk T. Verbeek" <dirk@example.com> wrote:

> What does not work for me is opening a pdf via the Outlook (company) web
> mail.
> Ah well, there are plenty of other pdf readers to chose from.

Firefox's external handler association is not involved when you click
hyperlinks in messages shown in Outlook. Outlook would use whatever are
the system-defined defaults for filetype handlers. So, that PDFs are
not handled by Firefox is wrong since Firefox was not involed. As for
why Outlook is not piping the PDF file to the OS-defined PDF handler
could be a problem in Outlook, or however you defined the PDF filetype
in the OS.

Outlook runs on multiple platforms, so no idea of which OS under which
you have Outlook running. There is no Outlook client for Linux which is
the OS you mentioned. So, somehow to use Outlook, you must be on
another platform, like Windows. For Windows, did you look at the
"Default Programs -> Choose default apps by file type" to see what
handler is associated with .pdf filetypes? In Windows, did you specify
Firefox as the PDF handler? Not a good choice as Firefox's pdf.js
handler is not as robust as other choices. If, for example, you are
running Outlook under WINE, you'll still have to see what filetype
associations are defined in your Linux setup as to which handler gets
used for .pdf files. Could be the currently selected handler is
inoperative, or got uninstalled but the filetype handler is still
defined.

On 5/27/23 23:54, this is what VanguardLH wrote:
> "Dirk T. Verbeek" <dirk@example.com> wrote:
>
>> What does not work for me is opening a pdf via the Outlook (company) web
>> mail.
>> Ah well, there are plenty of other pdf readers to chose from.
>
> Firefox's external handler association is not involved when you click
> hyperlinks in messages shown in Outlook. Outlook would use whatever are
> the system-defined defaults for filetype handlers. So, that PDFs are
> not handled by Firefox is wrong since Firefox was not involed. As for
> why Outlook is not piping the PDF file to the OS-defined PDF handler
> could be a problem in Outlook, or however you defined the PDF filetype
> in the OS.
>
> Outlook runs on multiple platforms, so no idea of which OS under which
> you have Outlook running. There is no Outlook client for Linux which is
> the OS you mentioned. So, somehow to use Outlook, you must be on
> another platform, like Windows. For Windows, did you look at the
> "Default Programs -> Choose default apps by file type" to see what
> handler is associated with .pdf filetypes? In Windows, did you specify
> Firefox as the PDF handler? Not a good choice as Firefox's pdf.js
> handler is not as robust as other choices. If, for example, you are
> running Outlook under WINE, you'll still have to see what filetype
> associations are defined in your Linux setup as to which handler gets
> used for .pdf files. Could be the currently selected handler is
> inoperative, or got uninstalled but the filetype handler is still
> defined.
>
Note that the OP says OUTLOOK WEB MAIL. Thus he's using Firefox to read outlook.com's mail. My best guess.
--
Linux Mint 21.1 Cinnamon 5.6.8
Al

Op 28-05-2023 om 12:57 schreef Big Al:
> On 5/27/23 23:54, this is what VanguardLH wrote:
>> "Dirk T. Verbeek" <dirk@example.com> wrote:
>>
>>> What does not work for me is opening a pdf via the Outlook (company) web
>>> mail.
>>> Ah well, there are plenty of other pdf readers to chose from.
>>
>> Firefox's external handler association is not involved when you click
>> hyperlinks in messages shown in Outlook.  Outlook would use whatever are
>> the system-defined defaults for filetype handlers.  So, that PDFs are
>> not handled by Firefox is wrong since Firefox was not involed.  As for
>> why Outlook is not piping the PDF file to the OS-defined PDF handler
>> could be a problem in Outlook, or however you defined the PDF filetype
>> in the OS.
>>
>> Outlook runs on multiple platforms, so no idea of which OS under which
>> you have Outlook running.  There is no Outlook client for Linux which is
>> the OS you mentioned.  So, somehow to use Outlook, you must be on
>> another platform, like Windows.  For Windows, did you look at the
>> "Default Programs -> Choose default apps by file type" to see what
>> handler is associated with .pdf filetypes?  In Windows, did you specify
>> Firefox as the PDF handler?  Not a good choice as Firefox's pdf.js
>> handler is not as robust as other choices.  If, for example, you are
>> running Outlook under WINE, you'll still have to see what filetype
>> associations are defined in your Linux setup as to which handler gets
>> used for .pdf files.  Could be the currently selected handler is
>> inoperative, or got uninstalled but the filetype handler is still
>> defined.
>>
> Note that the OP says OUTLOOK WEB MAIL.  Thus he's using Firefox to read
> outlook.com's mail. My best guess.

An excellent guess :)

Firefox has a build-in pdf reader and that's what I was using.

To recap, the Firefox pdf reader shows a blank page for documents from
the Outlook web client while other pdf readers show content.
Firefox als shows content for pdf's from non-Outlook sites.
And yes, this is Kubuntu Linux, until about a week ago things worked as
should.

Now there might be another problem, the Outlook web client likes to open
documents in their included Office 365 application...

For those not in the know, yes Office 365 runs on Linux.

"Dirk T. Verbeek" <dirk@example.com> wrote:

> Op 28-05-2023 om 12:57 schreef Big Al:
>> On 5/27/23 23:54, this is what VanguardLH wrote:
>>> "Dirk T. Verbeek" <dirk@example.com> wrote:
>>>
>>>> What does not work for me is opening a pdf via the Outlook (company) web
>>>> mail.
>>>> Ah well, there are plenty of other pdf readers to chose from.
>>>
>>> Firefox's external handler association is not involved when you click
>>> hyperlinks in messages shown in Outlook.  Outlook would use whatever are
>>> the system-defined defaults for filetype handlers.  So, that PDFs are
>>> not handled by Firefox is wrong since Firefox was not involed.  As for
>>> why Outlook is not piping the PDF file to the OS-defined PDF handler
>>> could be a problem in Outlook, or however you defined the PDF filetype
>>> in the OS.
>>>
>>> Outlook runs on multiple platforms, so no idea of which OS under which
>>> you have Outlook running.  There is no Outlook client for Linux which is
>>> the OS you mentioned.  So, somehow to use Outlook, you must be on
>>> another platform, like Windows.  For Windows, did you look at the
>>> "Default Programs -> Choose default apps by file type" to see what
>>> handler is associated with .pdf filetypes?  In Windows, did you specify
>>> Firefox as the PDF handler?  Not a good choice as Firefox's pdf.js
>>> handler is not as robust as other choices.  If, for example, you are
>>> running Outlook under WINE, you'll still have to see what filetype
>>> associations are defined in your Linux setup as to which handler gets
>>> used for .pdf files.  Could be the currently selected handler is
>>> inoperative, or got uninstalled but the filetype handler is still
>>> defined.
>>>
>> Note that the OP says OUTLOOK WEB MAIL.  Thus he's using Firefox to read
>> outlook.com's mail. My best guess.
>
> An excellent guess :)
>
> Firefox has a build-in pdf reader and that's what I was using.
>
> To recap, the Firefox pdf reader shows a blank page for documents from
> the Outlook web client while other pdf readers show content.
> Firefox als shows content for pdf's from non-Outlook sites.
> And yes, this is Kubuntu Linux, until about a week ago things worked as
> should.
>
> Now there might be another problem, the Outlook web client likes to open
> documents in their included Office 365 application...
>
> For those not in the know, yes Office 365 runs on Linux.

I missed the "web" word in your 2nd post. If they're running Outlook
Web (aka Outlook Web Access or OWA), doesn't that mean they're also
running MS-Exchange which would be a better choice, like using the
Outlook client in the MS 365 suite? OWA used to be called Exchange
Outlook Connect. OWA is a web app, but is an interface to Exchange, as
it was separate before but included with Exchange Server since 2016.
When I had to use OWA, it was because I was at home connecting to a DMZ
part of the corporate network to read company e-mail, calendar,
contacts, and tasks, because I didn't have Office at home to have
Outlook available. Later when I got Office (a perk from the company for
a single license, not one of their volume licenses), I switched from OWA
to the Outlook client to the DMZ corporate network (which required the
sysadmin to grant me permission/linkage to reach the Exchange server
from there).

There are several versions of PDF, and some are very old. A PDF viewer
may not handle old versions of PDFs. Only non-deprecated features in an
old version get migrated to the next version. Some info here on PDF
versions:

https://www.investintech.com/resources/blog/archives/7967-pdf-iso-standards-subsets-types.html

For me, on Windows since 7 and now on 10, Firefox is configured to use
an external PDF handler: PDF-Xchange Editor (aka PDF-XChange Viewer). I
think it supports back to PDF 1.3 (c.1999), but have yet to find a
concrete statement from the author. Some PDF viewers/editors don't go
back that far. While PDFs can contain Javascript, and can open attached
files (yep, PDFs can have attached files) when opened, I've disabled
those in my PDF viewer, unless the attached file is also a PDF. I've
only had to enable Javascript on some company and gov't PDFs (usually to
validate input is the correct type). You'll find external PDF viewers
have better security options and perhaps better old PDF version than the
pdf.js viewer included in Firefox. Also, pdf.js was not designed to be
a direct PDF viewer. Instead it was to convert PDF to HTML5, so the
output could be rendered inside a web browser. In addition, the
conversion creates an HTML <canvas> element, and Canvas is a known
attack vector to tracking (aka canvas fingerprinting). There are
anti-tracking add-ons that will block Canvas, and perhaps you have one.
Canvas didn't support everything that PDF can do, so Mozilla added an
SVG backend, but that still didn't do everything a PDF can do. With
PDFs, you can embed some or an entire font into the PDF to ensure a
recipient can read it as written, or no fonts are embedded in the PDF
and the recipient's host will try to use fallback fonts to best match,
but this can cause differences between what the author sees and what the
recipient sees, and the author could use some oddball fonts that have no
equivalent on the recipient's host. More info available at:

https://apryse.com/blog/pdf-js/guide-to-pdf-js-rendering

which notes:

PDF.js may be good enough if you require a short-term PDF solution for
when your requirements are limited and users can accept occasional
rendering inconsistencies, crashes, or slow performance.

There is a FAQ for pdf.js at:

https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions

Pdf.js will attempt to display some content in a corrupted .pdf file,
but no PDF viewer can guarantee to show anything if there is corruption.
I remember someone asking why their PDF viewer wouldn't open PDF 1.3
files, but their viewer didn't support really old versions. They had to
ask the sender to change the process they used to create the PDFs (it
was an ancient script using ancient tools). Rendering PDFs can be slow,
especially if lots of high-resolution images are included. You're also
running Javascript instead of a native app for the OS. A huge PDF will
take longer to render.

https://en.wikipedia.org/wiki/PDF.js
"PDF.js is performant for viewing most common PDF files, while it may
have some issues with large or 'graphics-heavy' documents."

You've found as most Firefox users have that pdf.js is a poor PDF
viewer. A heroic attempt, but not that great. Useful for small PDFs,
and with little graphics, and no Javascript. Almost every
non-Javascripted (native) PDF viewer is a better choice than pdf.js
included in Firefox and a Chrome add-on. You hit some wall on the
capabilities of pdf.js, and now realize a better PDF viewer is needed.
While I use PDF-Xchange Editor on Windows, there are other Windows and
Linux alternatives that are superior to pdf.js.

I found the below excerpt interesting because Firefox has it's own
anti-fingerprinting tech.

But, since today's Firefox update from 113.02 to 114.0 the pdf's are
again displayed!

Thank you very much for your explanation on how Firefox is rendering the
content of pdf's.

Op 28-05-2023 om 20:59 schreef VanguardLH:
> Also, pdf.js was not designed to be
> a direct PDF viewer. Instead it was to convert PDF to HTML5, so the
> output could be rendered inside a web browser. In addition, the
> conversion creates an HTML <canvas> element, and Canvas is a known
> attack vector to tracking (aka canvas fingerprinting)