Firefox Community Forum

Relevant to Firefox running on Ubuntu 22.04 Linux and an x86_64 platform.

Until roughly 2/2026, it was possible to load a security device by opening Settings, Privacy and Security, Security Devices, then browsing to a shared pkcs11 shared library, in my case /usr/lib/x86_64-linux-gnu/opensc-pkcs11.so, and clicking Load. The shared library would load and would be loaded subsequently whenever Firefox was started. For roughly the last two months, Firefox would pop up an error saying it was not possible to load the security device, but it would actually be loaded and it;s functionality would be available for the current session. For the last two weeks, the library would load without error, but only for the current session. Starting on 4/13/2026, some functions in opensc-pkcs11.so work, but not others. For example, it is no longer possible to connect to MS Teams web interface.

In Firefox Desktop 151.0 Beta 1, I'm experiencing a severe DNS leak even with DNS-over-HTTPS (DoH) set to "Max Protection". I've tried all available troubleshooting steps (including resetting `network.trr.*` preferences, disabling extensions, and testing in a clean profile), but the issue persists. > The same configuration works correctly in the previous version (150.x). Has anyone else encountered this regression?

I recently switched operating systems from W11 to Linux (Zorin), and installed a new copy of Firefox. I rely on local web pages I have written for some of my work, but the new copy of Firefox does not find the file. For example, when accessing an image, e.g., file:///magrathea/dmpase/home/index/coastal24.png, Firefox gives the message:

File not found Firefox can’t connect to the server at local file What can you do about it? Check to make sure you’ve typed the website address correctly.

The address is correct, that is, the file resides at: /magrathea/dmpase/home/index/coastal24.png and the user does have permissions to read the file. I've tried adding up to five '/' characters to the beginning, and I have turned off all of my installed add-ons, but without success.

An apparently related problem is that double clicking on a '.htm' file also changes the address, for example, from '/home/dmpase/Desktop/index.htm' to 'file:///run/user/1000/doc/f07a8988/index.htm'

And finally, the "Brave" browser is able to read the files with no errors.

How do I fix this for Firefox?

I need to install PKCS#11 modul on iMac (OS: Ventura 13.7.4) for signature authorization. I try: Settings-> Privacy and Security-> Certificates-> Security devices-> Load-> Modul filename: /Applications/CertiliaMiddleware.app/Contents/pkcs11/libCertiliaPkcs11.dylib , but I get an answer: "Unable to add modul". In order to install a certificate for signing with a card, I was informed that I need to install this modul first, but it doesn't work. What should I do? Thanks, Martina

I am unable to log into my energy provider, when I log into my bank I can't use some features like seeing all my transactions, I can't log into Twitter, I can't play anything from Substack.

I need help with annoying pop-ups. I followed instructing. It only say allow, not block, when I go to settings, security & privacy, checked block pop-ups and third party redirects.

A while ago when using the setting firefox noticed that i was using a vpn and turned the settings off. At least that was what i believed. Turns out, that only works with browser vpn addons that use the firefox settings. But these addons do not use wireguard, but tls to encrypt your data. If i use a vpn, and want to use the dns settings provided by them, i have to turn of the feature the dns over https feature from firefox. I only want to use that feature, if im not "protected" by a vpn solution of my choice.

Instead of returning directly to my desktop when I close Firefox, this website opens: https://www.websudoku.com/ and I then have to close that before I can see my desktop. I do not want this to happen!!!!! How can I stop it?

My wife's PC has had this problem twice. Somehow the default browser in Firefox gets changed to Rini.drorinat. How do I stop this from happening?

Some software must be lurking around resetting this. And don't tell me it's not a browser issue.

The attached pop up ad continues to present it self in spite of my selecting block pop-ups. I cannot find a setting to block the pop up depicted in the attached image. Assistance would be appreciated.