All Products Community Forum

I see this "File not found" error while trying to open few PDFs using Firefox browser. For example: Income Tax return acknowledgement. I am able to open the same PDF using other Android apps like Kindle, Google Drive PDF Viewer, Files by Google etc.

Gemini says ...it's because 'Firefox for Android' does not support content:// links treating it as a security risk. Here's a screenshot for your reference:

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!

In February this year I started having an issue with reading pdf formatted statements from my bank' (bank and personal information removed). Initially I thought it was some change at the bank so I sent the letter below to my bank.

Further experimenting with Microsoft Edge and Firefox leads me to believe the issue may be with recent changes to firefox. The attached jpg file shows the problem, though not a solution.

I would be curious to know if there is some (new) setting in Firefox to correct the problem.

Text of letter to bank:

re: document access on site

You have evidently made some changes in your account display and I have to tell you there are issues with it.

Previously the account document came up as PDF. Today I accessed the current statement and immediately noticed the change in display format.

I usually do two things here. First I print the document. The print button worked as expected. Next I SAVE a copy for future reference. The download button DID NOT WORK.

I had to use the print save to file function. This is where I found the problem. I saw this when I checked my print queue as well. Instead of PDF the document is now PDF.js viewer.

I have to ask why you went to java script when the original PDF format worked properly every time?

On the plus side, my pdf viewer still reads the saved file. It is the unnecessary print to file step to which I object.

I am not at all happy with this change and would encourage you to return to the previous process. Since it was NOT BROKE I am at a lost to understand WHY YOU FIXED IT.

I'm filling out an appcation for a study permit in canada. My university website said that i should download adobe acrobat reader and use it to open the application pdf. I didn't want to pay for adobe, so i opened it with firefox instead. In the document, there are tab selections that it allows so you can select answers accurate to you and fill out the document. But at the top of the document it says I should enable javascript by going to preferences, then edit, and and then reopen the form. How can I enable javascript in firefox? I'm having difficulty finding the preferences and edit sections.

When viewing pdf files created from MS Word (.docx) documents and sent to me I see white lines across some images but not all. This happens with Firefox on Windows 11 and linux mint (various versions). It is present on the images from the file as received and after uploading to a website. The images are OK if viewed using Opera or other browsers but the same problem is present on Thunderbird. The file below has the problem on 2 images when viewed on Firefox. https://www.kass.org.uk/Documents/NewsletterFrom251114/20260304%20March%20Newsletter.pdf I have caused the writer of the article a lot of trouble because I blamed her file which seems to be OK. Can you help? Thanks Brian

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

In previous versions of Firefox (up to version 133), it was possible to automatically trigger printing of a PDF file by loading it into an iframe from a sandboxed iframe and call print. However, starting with version 134, this no longer works.

Is there any other way to automatically trigger the print dialog for a PDF file in Firefox, similar to how it can be done in Chrome/Edge (e.g., by opening the PDF in a new window and directly triggering the print dialog without additional button clicks)?

The android version of firefox has a problem the displays a bar asking to download an open pdf whether the pdf is already downloaded or not. There's no option to turn off this bar that ends up blocking a lot of screen space. Maybe I'm missing something. Thanks for looking into this.

I am an academic. I use Canvas. When I am in Canvas and I try to open a document in it from Firefox, what I get are solid black pages. I do not have this problem with Canvas in Chrome or in Edge. I really don't want to use those Browsers. I actually have this problem with every PDF I try to open from all sites. This is a recent problem. But if I cannot correct it, I will have to use other Browsers.

E. Wray Bryant, Ph.D. [edited email from community support forum]

Hi, I am having an issue in mobile on iPhone 13 mini where I am trying to view a PDF (a bill so I can’t share the link) and it just opens to a about:blank page that says:

“Your bill is almost ready. Please wait.

Are you using a Chrome browser? Check your browser’s Downloads folder for a PDF of your bill.”

I wait and nothing happens. When I try in chrome it opens immediately in another tab (and doesn’t go to the downloads folder funny enough).

It isn’t in my downloads folder here either.

I don’t think it’s the site since it works in chrome.

I tried turning off pop up blocker, clicking the link again, and it didn’t change anything.

I also notice it is labeling the blank page as an insecure connection. It is from my city electric company so that wouldn’t be likely.

Thank you

1. Have read some recent questions which are similar. 2. My current Firefox is 151.04 (64 bit) I use Windows 11 Home 3. My problem relates to payroll in QuickBooks and has only occurred for payroll run after 20th May 2026. PDF's for payrun dated 20th May 2026 open with no problem. Any payroll reports after that date fail.

     I download payrun report and the page in firefox browser tab shows a 0 of 0 display (not the normal report)

      The file is sitting in browser download, as well as my C drive file explorer under 'downloads'

      When I double click, or highlight and select open, or highlight and select open with - my SodaPDF app displays a message indicating it failed to open a file.

4. Queried QuickBooks who believe it is a compatibility error.

5. Queried app provider (Soda PDF) and have been doing checks with them, but not able to resolve at this time.

6. Last resort went into QuickBooks using Microsoft Edge - file opened in SodaPDF with no problem.

As my preference is Mozilla browser, would like to have resolved ASAP, otherwise I need to use another browser. Await your advice - Kind regards

I'm begining to regret installing v146.0!

One of the most useful features of Firefox is the PDF editor and with this update, I've found that after annotating a PDF with several text boxes, clicking the text box icon (as shown in the attached screenshot) does absolutely nothing and it is impossible to enter any further text. The only way out of this is to refresh the pdf (after saving otherwise all changes will be lost) and then starting all over again only for the error to repeat itself making the editor almost unusable. Would really appreciate knowing how to work around this especially since to make my notes clearer, I change the color and the font size which is all lost everytime I have to refresh the PDF :-(

Incidentally, why are there so many updates? I prefer stable software that works rather than 'new features' that I never use!

Finally, Firefox used to have an amazing facility of making the Firefox private browser the default browser for Windows 10 but this was removed some years ago and can only be reinstated by changing registry keys. Everytime there's an update, these registry keys are overwritten :-(. Why was such a useful feature removed please?

Thanks in advance.

Hello

I have found the IOS App permit now to Save PDF in a better way Thank you so much for this

I have found also the Link : https://support.mozilla.org/en-US/kb/save-web-pages-pdfs-firefox-ios

Is Showing a way to save the PDF but probably should be update now

Thanks for your help Loic Coupel