"I am concerned that other users of Firefox who do not know how to do that will see pdf files of mine very badly reproduced and naturally will think it is my fault."

Exactly! Colors are lost. It is so compressed that things are illegible. My PDFs are accessible, but if you copy from the PDF to Notepad, each word, or part of word, is put on its own line.

I'm going to turn it off, but most important to me is for people see my PDFs as I created them. This isn't it.

TicketSource, (and others)

You may be interested in a related thread

• How to disable PDF.js built in viewer for my site/questions/951638

John99,

Not helpful, I'm afraid. Like donwiss, we have no control over which members of the general public choose to use our web site.

TicketSource,

.... Not helpful, .... we have no control over which members of the general public choose to use our web site. 

But you should be able to detect which browser is being used to view your site.

You could post your own advice and/or links to our documentation if you detect a user is viewing with Firefox.

If this is causing big problems, and/or the Firefox pdf.js viewer appears to be broken you could review the bugs list for changes and fixes, or even post a bug yourself.

John99, yes, you r correct. We are able to detect which browser & version are being used to view our sites. With that, we can show a message to ask our users turn off the ff's pdf viewer / disable pdf.js. However, the message means nothing here. The pdf viewer or pdf.js can be disabled already. We want to be able to read Firefox's pdf option in via JavaScript so that we can act accordingly at least (think 'noscript' tag).

TicketSource, as long as the "Portable Document Format" Content Type and other acrobat documents Content Type at 'applications' tab is not "Preview in Firefox", the pdf.js will not run.

Disable it please !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

"But you should be able to detect which browser is being used to view your site."

My sites are simple static HTML code. I have no inclination to figure out to detect which browser is being used.

"You could post your own advice and/or links to our documentation if you detect a user is viewing with Firefox."

Where? People find my site via searches and enter directly to the various pages and PDFs.

This should never have been released the way it is.

The PDF viewer should be able to view pdf s that is what it is designed for. Please post a link to your sites and say what the problem is.

Consider filing a bug @ http://bugzilla.mozilla.org/ if the viewer is not working and you are sure the pdf s are ok.

For those reading this and wanting guidence on disabling the built in PDF viewer:

In order to change the default reader for PDF files (to not open PDF files with Firefox's internal PDF reader), follow these steps:

1. Go to Tools > Options (or Firefox > Options).
2. In the Options window, select the Applications tab.
3. In the Search field, type PDF. You should find Portable Document Format (PDF).
4. On the right handside you should find an Action column. Use that to select your favorite PDF reader. In order to view PDF files in Firefox, choose Preview in Firefox.

John99, thanks you for your comments and its really appreciated. However, we are, in this post, at least until now, all aware that the ff's PDF viewer can be disabled manually. However, we are looking a method to detect the ff's "Portable Document File (PDF)" option setting programmatically. With that, please stop Let them eat cake. In fact, your " In order to view PDF files in Firefox, choose Preview in Firefox. ...." step will open the pdf with ff's build-in pdf viewer. If users want to view PDF files in Firefox properly, users need to select "user Adobe Acrobat (in Firefox)" instead. Most of us, in here, are really frustrated with the new ff's build-in pdf viewer already :)

This thread may well be viewed by users looking for assistance with disabling the built in viewer; that is why I thought it worthwhile to post the instructions.

I doubt it will be possible to detect the status of Firefox, but I do not know. I will ping Tyler by PM and I am sure he will give a definitive answer. (I do note this forum guesses Add-on information but that is from users who are logged in )

You say

 If users want to view PDF files in Firefox properly, users need to select "user Adobe Acrobat (in Firefox)" 

I disagree, the built in viewer should be designed to properly view pdf s and if it is failing a bug should be filed.

TYLER can you please help out with these answers.

John99, yes, you are correct; as you said "....the built in viewer should be designed to properly view pdf s..". Now, It is not. It fails to convert the pdf to html5 properly. In fact, a bug is filed https://bugzilla.mozilla.org/show_bug.cgi?id=739043 at last year's march.

edit: fix url error

taolo's comment above is useful, but the hyperlink to the bug report doesn't work correctly, it points to http://example.com/

This link does work correctly: https://bugzilla.mozilla.org/show_bug.cgi?id=739043

In fact it has been pointed out to me that this may be a relevant bug that interested individuals may wish to vote for or add yourself to the cc list

• Bug 845740 - The web site should be able to suggest that Firefox not to use the built-in PDF viewer

However unless you are a developer or the bug owner please do not add unnecessary & superfluous me too comments to the bug itself

This is a new feature and there will be quite a few bugs filed relating to it.

Bugs relating to enhancements or changes are likely to have to wait their turn for developer attention but IMHO anything actually broken needs fixing now as a priority.

John99, I think you're still failing to see this from the point of either end users who use PDF documents, or webmaster who publish them. For either of them, what used to work doesn't any more; it fails suddenly and without explanation. Again, migration to any new feature with potential bugs in it should be by conscious opt-in, not imposed by surprise on unsuspecting users.

I set Firefox back to using a helper application to open .pdf files from Preferences > Applications > Portable Document Format menu.

Hi ricpasco,
I do see and understand the problem, however as I repeatedly say this forum is for answering simple user support questions.

Sorry I am unable to give an answer that you consider satisfactory, but this forum is not for discussing developers decisions or feature enhancements you need to discus that elsewhere.

If something such as the current pdf viewer is considered broken file a bug. There is no point in complaining here because nothing can be done other than offering suggestions for users.

As for programmatically detecting what Firefox is doing I have already posted information, and we await any further information that Tyler the user advocacy representative may add.

For the record, when I viewed the pdf file reported by the thread owner, http://www.tmcc.edu/financialaid/downloads/forms/1213/FINAConsortiumAgree1213.pdf ....I got an infobar alert with the message,
This PDF document might not be displayed correctly
and a button, [Open with Different Viewer] that let me open the pdf file with my installed Adobe Reader application.

For anyone else having problems with the built-in PDF viewer, you can set Firefox to take a different action with PDF files (e.g., opening in Adobe Reader or in the Adobe Acrobat plugin) from the Options window - Applications panel drop-down menu for Portable Document Format (PDF):

Ref: View PDF files using Firefox’s built-in viewer