Firefox Community Forum

Starting a couple of weeks ago I haven't been able to open PDFs in my Firefox browser. Although there are other pdf viewers, Firefox has features that I use that the others don't. I've tried all the various ideas I've found elsewhere online but none worked. I submitted a ticket to our IT helpdesk, but they say it's a Mozilla Firefox issue. The error message isn't helpful at all, considering there is no web server involved.

I get the error below:

Access to the file was denied

Firefox can’t connect to the server at local file What can you do about it?

The issue is most likely with the website, and there is nothing you can do to resolve it. You can notify the website’s administrator about the problem.

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

Hello... currently when I try to open a PDF from the internet, I cannot open it in Firefox. Specifically I have been adding PDF files to a FB page, but cannot open the document when browsing in Firefox. I can open it, when using EDGE.

I closed a PDF file but can not move it to another folder. Windows says it is open in firefox. I closed firefox and it still says it is open in firefox. I even restarted windows and it still says it is open in firefox. How do I get firefox to close and release the file?

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.

So i reinstalled my graphics driver yesterday, and after that when i open a pdf on firefox it only shows blackscreen. it didnt happen on other browsers(chrome, edge)

Hello,

I can't save and download a modified PDF file.

To put it simple: I open a PDF file on Firefox; Rotate it clockwise; Open the Tools menu (»); Click Save; The saving window opens; I save the file; When I open it, the file is as at start, before rotating.

Windows 11 25H2 26200.7623, Firefox 147.0 Thank you for helping.

Trying to not just edit a PDF in Firefox on Linux but actually edit the document using its Dynamic-XFA format elements of that PDF. XFA is an Adobe proprietary format that they depreciated several years ago but it still works in Adobe Acrobat Free. (I use a Windows guest VM for this as a workaround for now but I'd rather not since it takes extra resources and time). Elements can be filled in FF and some menu drop downs work in FF but other dynamic XFA element buttons don't respond like the one I attached.

In Acrobat the "X" and "Add Contact" buttons will add or remove some elements to the document.

Can this be done in FF desktop?

Version 151.0.1 (64 bit) on desktop PC.

In about:config I know there are a lot of options to modify under the search term "pdfjs" but I don't know what element would allow this to possibly work if its supported.

I wish I had other better options but government documents are what they are.

Adding this post for SEO indexing purposes, as I cannot reply to the original archived one: https://support.mozilla.org/en-US/questions/1321170

The original post is one of the top search engine results, and provides a bandaid solution, without addressing the proper root cause, so I want to help whoever stumbles over this.

Original problem:

Dale 1/9/21, 8:26 AM

Firefox Developer Edition 85.0b4, macOS 10.15

If I Google for a PDF and click a link, I get the Firefox download dialog. If I select "Open with Firefox [Developer Edition]", the following things happen:

   The PDF is downloaded to ~/Downloads
   The PDF is opened in a new tab, with that new tab's location bar holding a file:///... URL to the downloaded PDF 

What I would instead like to happen is:

   The PDF is downloaded to some temporary directory where I won't have to worry about deleting it manually
   In whatever tab the PDF is displayed in, the location bar contains the URL where the PDF was (temporarily!) downloaded from 

How can I achieve this?

Not having the URL where a PDF was opened from is very annoying when, for example, I open a bunch of PDF search results to read and review, and I later want to share links to some of those PDFs. Best I can do to find their URLs to give to others is then to try and remember which tab corresponds to which search result, or do mine the downloads tab.

Contrast this with Chrome: I click a Google result for a PDF and the PDF just opens in the current tab with the URL to the PDF in the location bar. No dialogs, no PDF files hanging around in my home directory, and I can just copy the URL to the PDF the same way I'd copy the URL to any web page.

Thank you!

Proposed solution by original poster:

Dale Question owner 1/9/21, 9:27 AM Chosen Solution

Sigh. It appears the problem was one or both of the following preferences:

   pdfjs.enabledCache.state: false
   pdfjs.migrationVersion: 2 

I deleted both, and now clicking on a PDF just opens in the sane, normal way in Firefox that I desire.

Naturally I have no idea how those got set.

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 viewing a pdf that seems to be made of stacked images. While viewing this pdf in firefox it has these black lines between images, as seen in attachment, these change slightly as I zoom in. These lines do not appear when viewing the pdf in brave, see other attachment.

Also, this happens both on my desktop and laptop that have very different firefox setups.

How can I fix this without fixing the pdf?

How could I even fix the pdf?

Hello Mozilla Support Team,

I have been using Firefox for a long time, and recently I upgraded my Windows system. Before the upgrade, I had set Firefox to open PDFs directly in a PDF Reader other than Firefox’s built-in PDF viewer, and it worked perfectly. However, after the upgrade, Firefox now shows the "Opening when completed" message and opens PDFs slowly, instead of opening them immediately in my chosen PDF Reader.

I have checked the settings, cleared the cache, refreshed Firefox, and even tested with other software, but the issue persists. The settings for handling PDFs are still the same, but they don't seem to work as they used to.

Can you please assist me in resolving this issue? Any help would be much appreciated.

Thank you

Why has Mozilla decided to COMPLETELY IGNORE security settings applied to PDF documents? I have a number of PDFs secured so as to prevent the ability to print or copy text. When opened with Firefox, all of these settings are ignored.