Sorry the upload didn't work; you can reply to the thread with image attachments if you like. https://support.mozilla.org/questions/1230557#question-reply

Here is my comparison of page 20 in Acrobat vs. Firefox. I don't know where that other image is coming from...

It seems there are some elements that are hidden in some manner (I can't figure out how). If I experiment in Acrobat, I can see that making them visible causes a kind of chaos similar to what is displayed in Firefox. Example screenshots of one of my experiments are attached.

Whatever method the PDF uses to hide those elements isn't supported in the pdf.js library used in Firefox. You could submit an "Issue" for this on https://github.com/mozilla/pdf.js/issues

I think it's https://github.com/mozilla/pdf.js/issues/269. Nobody is working on it; this feature is not planned to be implemented.

TyDraniu said

I think it's https://github.com/mozilla/pdf.js/issues/269. Nobody is working on it; this feature is not planned to be implemented.

When I checked the layers pane in Acrobat, there weren't any layers in this particular PDF. I did see that issue in the following thread so I think this is a reasonable way to identify that issue: https://support.mozilla.org/questions/1210689#answer-1092664

You are talking technical matters that I don't understand at all. Why can Chrome and Edge produce correct pages in this PDF but not Firefox? I have not got this answer yet.

To simplify:

This PDF has some extra crap in it that Firefox's PDF Viewer doesn't know it should hide, so Firefox shows it. Other viewers such as Acrobat know they should hide it.

So I can hope for a fix? I have also seen a text form that is impossible to use in Firefox, but correct in Edge and Chrome. Interested?

I think someone needs to file an "issue" with the developers and see if they can figure out what is causing the problem. Then they should be able to predict how long it will take to fix.

For forms, I suggest using Adobe Reader/Acrobat outside of Firefox.

So I will give up the question about this PDF. But the text form I talked about is not PDF, it is a common HTML, where you fill in name, address, and data about what you are selling. Check this: https://www.ikea.com/ms/sv_SE/ikea_family/kop_och_salj/index.html Just now the form is completely invisible for me in Firefox. Then try Chrome or Edge!

Hmm, I don't see the difference on that page between Chrome and Firefox. since I used a Firefox private window, I did turn off Tracking Protection to load more third party content into the page.

I am so sorry, I copied wrong address. I mean this form page: https://secure.ikea.com/ms/sv_SE/ikea_family/kop_och_salj/secure/annonsera.html

So the form area doesn't load? Could you right-click, look for This Frame, and see whether you can successfully view the form in a new tab? The attached screenshot illustrates the menu on Fx U.S. English.

If it works in its own tab but not when it is framed, there could be some feature or add-on that is blocking "third party" content (it's an ikea.se page embedded in an ikea.com page, so that is considered third party).

How could anyone expect me to be able to figure out that this is considered to be an advertisement. After your explanation I disabled AdBlocker on this site, and poof - it worked! Thanks!

Hi hakan_lofgren, the way ad blockers work is pretty mysterious, always trying to outsmart disguised ads. I don't think ikea.se would be on a filter list of ad servers, at least not intentionally, so perhaps it is the way it was embedded that looked suspicious?? Anyway, it's always worth checking your content blockers when a page is not loading completely.