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 was in the process adding text for over an hour when the entire document flipped. It is a PDF I am editing on FireFox. I have done this many times on different documents without this problem.

I have noted other inconsistent behaviors--am I the only one?

Thanks any help, Marshall

I'm having trouble downloading product specification PDFs in Firefox from Formers Paper, a thermal rolls manufacturer. Some files open correctly, while others fail to download or display properly.

Has anyone experienced similar issues when accessing documents from a thermal rolls manufacturer website? Are there any Firefox settings or troubleshooting steps I should check for PDF downloads and file handling?

Thanks for any guidance.

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?

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.

I use Firefox as my default program for opening PDFs. But if I try to open more than one at the same time it will always leave one out and instead open a "New Tab" that I don't need. Can't figure out why or how to fix it.

Example: If I check (windows 11) files A, B, C, D, and E. It will open A, B, D, & E and a "New Tab" and leave out C.

Any Solutions?

I just went to The IRS and filled out a pdf form to change my address and the print or font was in blue text I Want it it to always be in Black font text please let me know how to do it. I have font contrast and blacken as extensions. Do I need to do t in my windows 10 computer

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

Firefox has been used to open PDFs. Suddenly, all the PDFs appear as totally black. If I hover over the tab for that PDF, it shows the little representation as normal white background. This just happened. Don't know how to correct for this.

Is there a way to set a default zoom for the firefox pdf viewer? The Automatic zoom has no toggle, and all pages open up as HUGE and I have to manually choose the zoom %. This is tedious and takes up time as I open many documents a day.

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.

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 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.