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Hi everyone,

After enabling `privacy.resistFingerprinting = true` in `about:config`, I noticed that Firefox’s built-in PDF viewer (`pdf.js`) is always displayed in **light mode**, even though my system and browser themes are both dark.

I understand that RFP forces `prefers-color-scheme: light` to prevent fingerprinting, but this also affects internal components like the PDF reader. Unfortunately, the PDF viewer doesn’t provide a manual dark mode toggle.

Is there any **official or safe workaround** that allows keeping RFP enabled while still having the PDF viewer use dark colors?

Thanks!

I am a Dropbox user. I have until recently been almost strictly a Google Chrome user. The PDF seamless behavior I have been seeing in Chrome is like this: 1. If I click on a search engine result for a PDF, I see the PDF opened in the browser. 2. If I click on Download at Dropbox, the PDF is downloaded to my PC.

On installing Firefox, the behavior I saw was like this: Whether I clicked on a search engine result or Download at Dropbox, I saw the PDF opened in my browser.

When I changed the Action for Portable Document Format (PDF) (application/pdf) and Portable Document Format (PDF) (application/binary)to "Save File", the PDF downloaded to my PC. But so did search engine links.

I seem to have fixed the issue by making my settings like this: 1. Action for Portable Document Format (PDF) (application/binary) to "Save File" 2. Action for Portable Document Format (PDF) (application/pdf) to "Open in Firefox"

Fingers crossed. ??? I was wondering why it wasn't set up this way on installation.

I am a magazine editor right on deadline and as my Firefox inisted it must be updated I endeavoured to do so and now it will nor allow me to open up and forward any pdfs.Please help.

I'm trying to use Firefox to fill out my tax forms, but while I can save them and view them with Firefox, they're blank when I open them with Adobe or print them. This is, to say the least, NOT USEFUL. What is happening?!?? I'm using Win10 and the latest version of Firefox, and I tried it on an old Mac with the latest version of Firefox as well.

Lately, whenever I try to open a PDF from a website open in Firefox, the tab crashes and the PDF does not open. An error stating that the Windows file-dialog has crashed is displayed at the top of the tab. I tried to attach a screenshot of the error but that action only generates another error.

This condition does not occur when I try to open the same PDF from the same website open in either Chrome or Edge, the PDF opens properly which leads me to believe the problem is in Firefox and not my Adobe installation.

Thank you

How do I get the PDF viewer to work again? For years I have used the setting "save" to automatically download. Now I am unable to view them without going in and changing the settings to "open in firefox". I would like to continue to use the save setting without having to constantly change this back and forth. When I click to open the file, all it does it grey out.

Every time I try to view a pdf file on Firefox I can view the file but in the lower right 1/4 of the screen I get a graphic of a page with shaded areas representing lines with writing on them. There is a type of pen cursor moving along the line.

This happens with different pdfs - from the internet and from my saved files. This doesn't happen on another computer with Firefox.

I've deleted and redownloaded Firefox an number of times, also tried troubleshoot mode - no improvement. Virus scanned, restarted a number of times.

Pdfs work on edge and chrome and reader with no problem.

I have a screenshot.

Any Ideas? Thanks