User Agent: Opera/9.80 (Windows NT 6.1; WOW64; U; en) Presto/2.10.229 Version/11.62
Steps to reproduce:
On my site PDF files are used for printing purposes. Starting with v19 the PDF.js built in viewer is used instead of Adobe acrobat plug-in. This change has broke an existing functionality (see https://bugzilla.mozilla.org/show_bug.cgi?id=845724 and https://bugzilla.mozilla.org/show_bug.cgi?id=845733)
The pdf file is not printed automatically and has poor quality if they are printed manually. Also PDF.js can have some rendering issues and it hard to support additional pdf viewer. So for my site built in PDF viewer should be disabled at all. I've found no way to do this at the site level. I think that the instructions for disabling the new feature is too complex for ordinary users and it easier to ask them to use another browser.
The web site should be able to force the browser to ask the user that for working properly with this site the built in PDF viewer should be disabled. And if user is confident with the site and decided to disable it this should be done in one click.
Likely a dupe.
You can only force a file save as window for the PDF (with a content-disposition:attachment header)
One related discussion on a sumo support question is: https://support.mozilla.org/en-US/forums/contributors/708997
Also note related subjects are considered important enough to be included in the very restricted current sumo hot topics page https://support.mozilla.org/en-US/topics/hot
linking to https://support.mozilla.org/en-US/kb/disable-built-pdf-viewer-and-use-another-viewer
but IIRC someone; elsebug; suggested a whiteboard or similar tag for bugs with a sumo interest/importance I cannot find that at the moment,I guess nothing came of it)
Allow the webpage to not use the build in PDF Viewer is a bad idea in my case. We should instead concentrate on fixing the problems (e.g. the printing ones you've mentioned).
I too am having a lot of difficulty with built-in PDF Viewer. I use Adobe PRO with multiple real estate sites that have their own fillable PDF forms. After updating to V19, I could NOT use Firefox at all to complete my report tasks. I eventually used System Restore to roll back and start using Firefox again. PLEASE allow the PDF Viewer default to be a CHOICE upon updating.
(In reply to RealtorRobin from comment #5)
> I too am having a lot of difficulty with built-in PDF Viewer. I use Adobe
> PRO with multiple real estate sites that have their own fillable PDF forms.
> After updating to V19, I could NOT use Firefox at all to complete my report
> tasks. I eventually used System Restore to roll back and start using
> Firefox again. PLEASE allow the PDF Viewer default to be a CHOICE upon
You can switch back to acrobat by following https://support.mozilla.org/en-US/kb/disable-built-pdf-viewer-and-use-another-viewer?esab=a&s=pdf&r=3&as=s
*** Bug 848690 has been marked as a duplicate of this bug. ***