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Don't like the new pdf.js viewer. How can I disable it and restore Acrobat Reader as my preferred plugin?


I really don't like the look-and-feel of the new pdf.js viewer. On my machine (6 yr old HP running Windows XP with sp 3) it displays slower than Acrobat Reader did, and I was perfectly happy with Acrobat Reader plugin. Frankly I want to disable pdf.js, but haven't been able to figure a way to do it. It doesn't display anywhere I could find on Add-ons Manager. I don't want to be compelled to use a feature that seems to be a performance detriment, at least for me. Mozilla, please rethink this!

Chosen solution

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

See also:

Read this answer in context 21

Additional System Details

Installed Plug-ins

  • Google Update
  • Adobe PDF Plug-In For Firefox and Netscape 11.0.02
  • Next Generation Java Plug-in 10.13.2 for Mozilla browsers
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Google Talk Plugin Video Accelerator version:
  • Version
  • Shockwave Flash 11.5 r502
  • RealPlayer(tm) LiveConnect-Enabled Plug-In
  • RealPlayer Download Plugin
  • VLC media player Web Plugin 2.0.2
  • RealNetworks(tm) RealDownloader Chrome Background Extension Plug-In
  • RealNetworks(tm) RealDownloader PepperFlashVideoShim Plug-In
  • RealNetworks(tm) RealDownloader HTML5VideoShim Plug-In
  • RealDownloader Plugin
  • Garmin Communicator Plug-In
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • RealNetworks(tm) RealPlayer Chrome Background Extension Plug-In
  • RealPlayer(tm) HTML5VideoShim Plug-In
  • Adobe Shockwave for Director Netscape plug-in, version
  • 5.1.10411.0
  • iTunes Detector Plug-in
  • DivX Plus Web Player version
  • AmazonMP3DownloaderPlugin 1.0.15
  • DivX VOD Helper Plug-in
  • npmnqmp 989898989877
  • Garmin Communicator Plug-In
  • getplusplusadobe16248
  • 1.9.0042.0
  • Windows Presentation Foundation (WPF) plug-in for Mozilla browsers
  • DRM Netscape Network Object
  • Npdsplay dll
  • DRM Store Netscape Plugin
  • Office Plugin for Netscape Navigator
  • Windows Multimedia Services DRM Store Plug-In


  • User Agent: Mozilla/5.0 (Windows NT 5.1; rv:19.0) Gecko/20100101 Firefox/19.0

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Helpful Reply

hello, if you want to switch back to the plugin you've used before to view pdfs just go to firefox options > applications & define the default action for the portable document format (pdf).

View PDF files in Firefox without downloading them

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10738 solutions 96627 answers

Chosen Solution

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

See also:

Question owner

Madperson's suggestion didn't work the first time I tried it. Once I followed the advice from cor-el and disabled the pdf.js, it did work! My Adobe Reader once again works inside Firefox, just as before. I can also download, of course. Thanks to you both.

BTW in Firefox Options > Applications the portable document format still appears (at least on my machine) as Adobe Acrobat Document.

taildragger-j3 0 solutions 2 answers

I have done ALL of this multiple times and Firefox still tries to open in pdf.js and it is trying to read the pdf in Word!!!!

This is an absolute crock. I guess I'm going to be forced to Chrome

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10738 solutions 96627 answers

You can delete the mimeTypes.rdf file in the Firefox Profile Folder to reset all file actions.

VikkiO 0 solutions 4 answers

Regarding firefox changing my default preference for Acrobat when updating to v 19...it was extremely rude. Hopefully new updates will honor my preferences as I've set them.

Modified by VikkiO

taildragger-j3 0 solutions 2 answers

I tried this to no avail. STILL doesn't let me prevent the stupid pdf.js

You can delete the mimeTypes.rdf file in the Firefox Profile Folder to reset all file actions.

piotrnm 0 solutions 2 answers

This pdf.js viewer is crap. It can not print properly.

rsbrux 0 solutions 6 answers

As bssjersey points out, FF19 ignores your "Application preferences", described [https://support.mozilla.org/en-US/kb/change-firefox-behavior-when-open-fi...] here and [https://support.mozilla.org/en-US/kb/view-pdf-files-firefox-without-downl...] here as long as pdf.js is enabled. This is counter-intuitive and user-unfriendly. One shouldn't have to override settings (disable pdf.js) in about:config for an option configurable in the regular GUI to work as expected.

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10738 solutions 96627 answers

If you select setting other than Portable Document Format (PDF) (Preview in Firefox) in "Tools > Options > Applications" then Firefox shouldn't use the integrated PDF Viewer.

rsbrux 0 solutions 6 answers

It shouldn't, but if I select "always save" in my preferences for PDF, FF19 still opens the PDF in pdf.js instead of presenting the save dialog, unless I have disabled pdf.js. Judging from his/her post above, bssjersey had a similar problem. P.S. It also doesn't respect my choice of PDF Xchange to view PDF files.

Modified by rsbrux

jharri 0 solutions 2 answers

It would be extremely helpful if Godzilla or whatever monster you are out there stopped immediately forcing updates which without prior notice go and change the basic behavior of the software, but rather concentrated on providing security updates of this browser of notoriously inefficient coding and poor performance, if absolutely necessary.

This time I thought that it must be some vicious malware that had captured my machine and disabled my Acrobat plugin. Thank God I managed to restore it, but this took far too much time. Unfortunately I'm no schoolchild any more and just wouldn't have time clearing your messes.

I know that there aren't many among you to understand. Thanx anyway for taking this into consideration, even though I'm quite pissed of on you.

jharri 0 solutions 2 answers

Oh how beautiful. In Wikipedia I discovered the existence of the corporate version Firefox ESR and immediately "downgraded" to that one, in the hope that it really wouldn't trouble me with unnecessary and unwanted "upgrades" every couple of weeks.

You folks should advertise the ESR version much more, so that not that many disappointed customers who you try to make use of as involuntary beta testers wouldn't go for Chrome, or even Safari or Opera.

Question owner

Just read about FF ESR. I had no idea it existed. I don't plan to "downgrade" to it, though, unless Mozilla burns me again with another change like the one to pdf.js. I don't object to being a beta tester. Wide rollout seems to be essential to development of new web software - the bugs have to be exposed somehow. All I'd ask of Mozilla is something like a system restore function, so a user could revert to the last version that worked for him/her.

frogguy 0 solutions 2 answers

Whose idea was this pdf.js piece of garbage? It's horrible. It's hideous. It's slower than death. I'm really getting tired of these little surprises every couple of weeks in Firefox. I'm seriously ready to switch to something else, but they've all gone to pot too. Chrome is so much slower than Firefox I refuse to use it, except that I MUST use it sometimes because Firefox will no longer function when I'm using certain other programs. Firefox loads to a black screen and freezes.

I'm going to check out this ESR version. I'm really tired of having to spend an unexpected hour to fix my Firefox installation every few weeks. Adobe's Acrobat reader wasn't broken. Why did we need to "fix" it with this pdf.js piece of crap?

Oh, and for the record, I'm a former professional software tester who worked for WordPerfect and Novell. I know my way around testing software. Even still, I don't like these surprises.

Update - So I've disabled the stupid pdf.js and now I can't read PDF files at all in Firefox. I reinstalled Acrobat Reader hoping it would reconnect with Firefox, but no, all I get now is an option to download the PDF to my hard disk, which I don't usually want to do.

Was this really necessary? Why can't you just give us a revert option to go back to what we had? What made you think this pdf.js reader was ready for prime time? It's like replacing a fine car with a one-speed bicycle that's missing a pedal. Seriously boys, can't you at least give us the damned instructions to get Firefox working as it always has? This is absolutely unacceptable.

Modified by frogguy

sneezer2 0 solutions 1 answers

Mozilla, are you the ones who did this.

You had NO RIGHT and I am pissed. You DID NOT ask if you could and I didn't ask for it. It just appeared and began screwing up every time I want to display a .pdf. There is usually a warning that the file may not be displayed correctly and often some pages are blank. Frequently, the document will not print correctly.

You have willfully ABUSED the trust of your users.

I am going to get rid of this piece of CRAP CRAP CRAP and if the process requires getting rid of you too, I will also do that. I do NOT LIKE companies that force their own choice of software into my private machine without permission.


silviac 0 solutions 4 answers

I disabled the FF viewer and set the option for .pdf files to download. An unknown file type downloads. If I set the option for PDF Xchange or Adobe Acrobat Viewers, the file will open in view, but of course it is not editable, so I have to save it, then open Adobe or PDF XChange and then find the saved filed and then edit it.

Why can't I just download the file like before and have it open automatically in my default pdf handler? Everything was so nice before FF 20 screwed it up. Please tell me there is a way to actually download the pdf directly from the web link again.

Question owner

Does anyone on this forum know how to get Mozilla to actually pay attention to all these complaints I'm seeing here about pdf.js? Maybe we should try sending an old-fashioned letter via snail mail. I was talking to a Congressional staffer last week, and he told me that paper letters get far more attention these days because they take more time to prepare and cost the sender something (postage, plus the cost of paper & envelope). That demonstrates what the pols call "intensity," i.e., depth of commitment to whatever cause you're writing about. Anybody got a suggestion about whom to write to?

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From within Firefox use Help > Submit Feedback... to let Mozilla know how you feel about Firefox and its' features.

Question owner


I should have known that! I will send Mozilla a note with a link to this discussion. Hope they actually listen to such things. Guess I'll find out.