Firefox Community Forum

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!

Hi all, I remember in older versions of Firefox (within the past 6 months) that pdfs embedded in a page would be a hyperlink that you had to click which would open in another tab. Now pdfs automatically open which is very annoying as it makes it difficult to read, while I found a way to open it in another tab I was wondering if there is a setting I can disable so I can just click on a hyperlink.

Thanks in advance

Using Firefox 143.0 on Ubuntu 24.04, when loading PDFs into the browser window, the PDF does not get properly rendered. Instead, when scrolling part or all of the PDF just show the desktop or windows behind Firefox. This usually happens after opening several PDFs and then keeps happening until I restart Firefox. Is there an issue for this extremely annoying bug?

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.

Hi Firefox Team,

Why suddenly today there's no PDF preview for all PDF file sent or received on browser (i.e whatsapp web) Attached latest screenshots

Please assist.

Regards, Novie

I am using the FireFox PDF Editor to annotate a PDF, however, no method of me saving the document (whether that is save as, or save as PDF) will allow me to save any annotations on the document. If I try doing save as PDF, the preview shows up as blank sheets of paper, when I click "save as" it only saves one page of the 31 as BLANK. If I try doing normal save as, the saved file is un-annotated.

Please help... thanks

Dear Firefox Support Team,

I am encountering an issue where PDF files fail to display properly in Firefox, appearing as blank pages. This problem persists across multiple PDF documents, suggesting a potential browser compatibility or configuration issue.

Request: Please investigate this behavior to identify the root cause (e.g., rendering engine, plugin settings, or recent updates). Adjust Firefox’s default PDF handling settings or implement necessary fixes to ensure proper PDF display.

Additional Details:

• Firefox Version: All
• OS: Windows & Mac
• File link: https://res.mdpi.com/data/pharmaceuticals-18-00847-v4.pdf
• Steps to Reproduce: Open any PDF file → Blank page appears.

This issue impacts productivity and user experience. Kindly prioritize resolving it or provide workarounds. Thank you for your attention.

Best regards, Mia Yu [email removed]@mdpi.com/[email hidden]@qq.com

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

Firefox 138.0.1, MacOS Monterey 12.3

PDF files: settings is set to "Always ask" (see attached) However, when I click on a PDF link, and get the dialog "Open With" is grayed out, and the only option available is "Save File" (see attached screenshot). (A few weeks or months ago it all worked correctly.)

Is there a way to get "Open" working again?

Hello: recently I decided to ditch expensive PDF Converter apps for my desktop pc as overspecified for my purposes. To date, I haven't found any guidance to use the Firefox Easy PDF Converter - usually required to convert Lotus Word Pro or MS Word text documents to pdf format. As a second request, can it be used to reverse convert e.g. pdf to docx etc. I have already added it to my Firefox app, but can't go any further. Thank you for helping. Geoff Pickerell (UK)