hello, firefox 19 has introduced its own integrated pdf viewer - if you want to switch back to the plugin you've used before to view pdfs just go to firefox options > applications & scroll down and define the default action for the portable document format (pdf).

View PDF files using Firefox’s built-in viewer

Thanks. I tried resetting the default to both "Adobe Acrobat" and "Adobe Acrobat (in Firefox)". Either way works to get a properly displayed pdf, although both seem to be a little slow. I left it on "Adobe Acrobat (in Firefox)".

What's wrong with Firefox's built-in pdf viewer? Does it have a bug that needs to be fixed?

The integrated PDF viewer is still under development and works fine for simple PDF files, but a lot of advanced features aren't supported yet and there are still a lot of bugs open.

• https://bugzilla.mozilla.org/buglist.cgi?product=Firefox&component=PDF%20Viewer&resolution=---

(please do not comment in bug reports: https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)

I sure hope that this BUG will be fixed soon, it is a big BUG, my professional pdf document was destroyed by the viewer, it does not handle transparencies in the document pdf at all, ....there are no simple pdf files anymore except plain word documents....clients will be contacting me to find out why my beautiful pdf brochure looks so bad on the web - I am happy to have found this explanation though - firefox has been having more and more problems lately - I am wondering why firefox would move away from the Acrobat Reader when that is so common everywhere on the web

For now you can try this workaround and make use of Bug 738967.

Using an embed tag seems Firefox making to use the Abode Reader plugin in Firefox and an object tag defaults to the build-in PDF Viewer if enabled.

• http://forums.mozillazine.org/viewtopic.php?f=23&t=2649203
• bug 738967 - pdf.js doesn't work for embedded PDFs

I followed both of the work around solutions posted both in preferences and adjusting the disable value to true. Neither solution has corrected the problem. I use Firefox for a cloud based inventory software and I have to download and print PDFs everyday so this issue makes Firefox less attractive then IE.

My question is simple - why would you put an application in production that has a lot of bugs? To replace a good and steady Adobe product? My customers will believe that I put a pathetic fallible form online. They are not sophisticated on computers so I just tell them to use IE. Ugh

I must agree with pgwebgirl!

I started seeing the error bar 1-2 months ago on all PDFs that are fillable (such as IRS forms). The PDFs display but cannot be modified. I have switched Options -> Applications back and forth between "Use Adobe Acrobat (in Firefox)" and "Use Adobe Reader (default)", shutting Firefox down and restarting it each time, of course. There is no change in the symptom either way. Actually, there are three PDF entries in my application table, and I changed all three of them:

- Adobe Acrobat Forms Documents (application/vnd.adobe.xfdf)

- Adobe Acrobat Forms Documents (application/vnd.fdf)

- Adobe Acrobat XML Data Package File

System and product levels:

- Windows 7 Home Premium SP1

- Firefox 19.0.2

- Add-ons Manager says the Adobe PDF Plug-In is Adobe Acrobat 11.0.2.0 for Firefox and Netscape. Last Updated Friday, February 15, 2013

- Adobe Reader XI Version 11.0.2, which works correctly outside Firefox

I do not have Adobe Acrobat installed.

You can set the pdfjs.disabled pref to true on the about:config page to disable the build-in PDF viewer.

You can also check the value of the plugin.disable_full_page_plugin_for_types pref and remove the application/pdf part if present.

• http://kb.mozillazine.org/about:config

See also:

• https://support.mozilla.org/kb/view-pdf-files-firefox-without-downloading-them

Setting pdfjs.disabled to true was not what I wanted; it just forced the PDFs to be downloaded. But removing application/pdf from plugin.disable_full_page_plugin_for_types solved my problem.

Note for other novices: DON'T click reset on that pref. The reset value is empty, and there is no "un-reset", as I learned to my dismay. Just modify it as cor-el said.

I have been a preferred user of Firefox for many years and encourage my clients to install it on their systems. However, lately I and many of my clients have been experiencing terrible trouble with downloading pdfs. I know you have answers in regard to disabling etc but when I upload a pdf to a website and it doesn't view properly in FF, you cant explain that to everyone who visits the site. TO me it's unacceptable to launch something that is only half baked. I deal a lot with the tourism industry and many of my clients are uploading nice brochures to entice visitors but the pdfs in FF are looking very uninviting and that is not the case. I hope this issue will be seriously looked at and either removed until it's fully functioning properly or giving a clear option to viewers that they can view it in Adobe Reader as well.

In FF Verison 22.0 and Nightly Build 25.01, Windows 64bit this or a similar problem is yet not solved with (default) setting "Preview in Firefox" for Type pdf:

The embed Element src attribute is called multiple times (in my case it is a relative link) and the Response Content-Type is set to text/html. An embed Element with type application/pdf has NOT set the HTTP Header Content-Type application/pdf.

The reason seems to be that the base URL is not set properly: Instead of using the base tag element (in our case ending with a slash) the current URL (page address) is used! All the other errors seem to be subsequent errors...

If I change the Setting to "Ask..." the Content-Type is not set either, but the web server handles this correctly responding at least with the correct type.

This is a not resolved bug in my eyes:

"A embed Element with type pdf having a relative src attribute appends to page address URL instead of Base url (mode Preview in Firefox)".

P.S.: If I change the embed src - Element to an absolute URL anything works fine!