Firefox Community Forum

Opening PDFs automatically with Firefox and, without any changes I might make, saving them with the download function in Firefox, actually ruins the functionality and data entry function of that file. Specifically this happens with PDF files downloaded from the (not all that amusing) PDFs from the FINCEN, (US Financial Crimes Enforcement Network). I do not see why and how Firefox thinks it is allowed to change files that are simply downloaded and saved on Firefox.

In other words, it seems that Firefox strips away certain "permissions" and/or "functions" (like built-in lookup, menu or choice boxes). This means that the file so downloaded via Firefox can no longer be used to properly fill in data, or to look up and choose data items within the file. (I see many times that ANYTHING having to do with "permissions" tends to be an intractable and unsolvable problem for software makers & experts, so, if you do not know right away how to solve the problem, it will probably take you several years to figure this out.)

The PDF in question is created by a government agency. If you have ever dealt with a government agency, then you know that they act sort of like Adobe or Microsoft: "They don't respond, or they do respond & say they do not understand, and if they understand, they are either unwilling or unable to fix the problem."

If there is a switch or option within Firefox, which lets me tell Firefox "Save this file exactly like it is received, nothing added or removed!", that would be nice. I just have not found such an option yet, and it would be nice if it might get provided someday.

I will share my browser data, but I am sort of convinced that a detailed question like mine will not be addressed within that shared data.

I am following directions that advise to go to Settings and change the option to open PDFs as individual files. Currently, they are opening as a Firefox tab. I have tried several times to make changes that stick, even rebooting. But PDFs still open in a tab.

Please help. Thank you.

Hi everyone,

I’m running into a frustrating issue where Firefox is opening PDFs in two places at once.

The Problem: When I click a PDF link, Firefox opens the file in a new tab (internal viewer) but also launches the standalone Adobe Acrobat app to display the same file. I only want it to open in Firefox.

Details: - Settings: My "Applications" setting for PDF is currently set to "Always Ask." - The Glitch: Even when I manually select "Open in Firefox" from the prompt, Adobe Acrobat launches anyway. - Timeline: This started happening 2 days ago without any manual setting changes (I think it might be after a firefox update? I might be mistaken)

- Troubleshooting done: I have tried toggling the action to "Open in Firefox" directly, but the dual-launch behavior persists.

Thanks

The attached shows the cursor only from today and free hand highlight from a March 2026 when working properly. The free hand highlight today does not highlight, only the cursor highlight is functioning.

PDFs seem to keep turning black when a pdf appears on Firefox and Downloads with Firefox. The preview of pages is still intact. Turning off hardware acceleration does not solve the issue. How do I fix this problem?

Mozilla/Firefox is my browser. Lately, every time I am on a website where I need to open a pdf document, like a bank statement I want to download, a pop-up appears that advises me to sign on the dotted line or anywhere and shows a little pen writing something. Underneath is this sentence: "Draw, type or upload your signature, then place it exactly where you want. Save your go-to signature for next time."

Where did that come from? It blocks my view of the document and if i try to capture it in a "screenshot" nothing appears. Is this a Mozilla/Firefox thing or a (Acrobat) pdf thing? And what can I do to stop it?

I have Firefox set to always ask about how I want to open/save PDF files. Within the past couple weeks, I've encountered an issue with opening PDF files. When I click on a PDF and select "open with Firefox," the PDF opens in a new tab on Firefox, but it also opens in Acrobat. When I select this option, I just want the PDF to open in my browser, and I cannot find a way to stop it from simultaneously opening in Acrobat.

In the past, I was able to freehand highlight PDFs that did not recognize the Text. I was using this function this week; maybe the newest Firefox update is at fault. Without this, half of my documents are not really usable in Firefox. Everything else works. If it recognizes the text, I have no problems; the pencil tool also works just fine.

Firefox 137.0.2 64 bit

I've recently set up on a new desktop running windows 11.

My previous setup had windows 10, but the same version of Firefox.

In the past, when building web pages in php, I'd always used Firefox to preview the html elements of pages offline. I've not used a testing server on Windows as I'd rather test the PHP elements on the live server. Firefox was just for testing the html / css design elements, which it worked very well for.

Now, on my new computer and windows 11, when I try to open a php page offline with Firefox I get a window asking me what to do with the file - "open with" or "save file". When I choose "open with" and choose Firefox, Firefox opens up another tab with the address of the file in the address bar, but no content below, and then another window pops up asking me what I want to do with the file. This goes on indeffinately if I keep clicking "open with". There's no issue with the files I'm trying to open as I can open the exact same files on my win 10 computer with the same Firefox version and the display just fine. What's going on?

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.

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, would I be able to get a free PDF reader? I have few items on my computer face and I can not open a PDF say of one of my laminating machine. do Firefox or Mozell have a PDF reader I can download for free?

Bob Robertson

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.