Firefox for Enterprise Community Forum

We followed the links below to block internet access in Firefox browser:

https://www.youtube.com/watch?v=fAGYYX5hYb8 https://github.com/mozilla/policy-templates/releases

We downloaded the ADMX and ADML files. Using these files, we were able to locate Mozilla Firefox in Group Policy Management and successfully block all websites in the Firefox browser using the pattern :///*.

However, we encountered an issue with exceptions. We do not wish to block certain websites, including localhost. We attempted to use the "Exceptions to block websites" option, providing values such as ://msn.com/ to exclude specific sites. Unfortunately, this approach did not work as intended. For instance, msn.com is one of the websites we want to allow, among others and also localhost.

We require assistance with the following issue: "Exceptions to block websites" is not functioning properly within the group policy of Mozilla Firefox.

Hi,

just downloaded the latest Policy Templates in Version 7.7 and installed them in our Central Policy Store. I went through all the settings but cannot find a configuration allowing us to block downloads of eg. executable files .

Even safebrowsing is not included to configure.

Any ideas?

Hello Everyone,

I am seeking assistance to configure Firefox browser so that internet access is blocked when the browser cannot download or access the proxy Auto-configuration (PAC) file. Our organisation enforces all web traffic through proxy servers defined by a PAC file. For compliance and security reasons, users should not have any direct internet access unless the browser is able to successfully retrieve and apply the PAC file.

The desired behaviour is:

1. Firefox attempts to download the PAC file from a defined URL. 2. If the PAC file is unreachable or fails to load (e.g., due to network restrictions or the device being outside the corporate network), Firefox should "fail closed" - meaning it should not allow any direct internet traffic. 3. This is effectively a "fail-block" mode: no fallback to direct connections, and no cached or bypassed proxy settings should allow internet browsing.

This behaviour is critical to prevent devices from accessing the internet without applying corporate proxy rules. I would like to know:

1/ Whether Firefox currently supports a setting or policy that enforces this fail-block condition when the PAC file is unavailable. 2/ If not, whether there are recommended configurations or enterprise policies (e.g., via `policies.json` or Group Policy templates) that could achieve equivalent enforcement.

Thank you for your assistance and guidance.

Hello

We want to set up a GPO that when users exit their Firefox browser, all of there cookies and cache gets deleted.

How do we do this?

Thanks

I have several users that are running Firefox 137. When attempting to update, they get the message that the organization has blocked updates. There is nothing I can see that we have done. Attempted to update registry and .json file. I cannot find where the block is coming from. Do I need to delete and reinstall?

Hello!

I manage our browser configuration for our enterprise. We use group policy to restrict browser addons until they clear our internal security review.

I'm looking for a way to allow specific addons using group policy, while generally blocking everything else.

I've found the setting to enforce the installation of addons, but we'd like to avoid forcing every addon to install on every system as there would be overlap between things like password managers and such.

Is there a way to accomplish this?

Firefox version

   128.2.0esr (64-bit)

Operating system

   Windows 10/Windows11 23H2 Septembre patch

Hello everyone,

maybe you can tell me/explain what the problem could be.

In our company we had Firefox version 115.14.0esr (64-bit) and then we updated to 128.2.0esr (64-bit).

Since version 128.2 ESR we have experienced problems in Firefox when trying to access DNN+ pages (with login). https://www.dnn.de/sport/regional/dresdner-sc-denkt-ueber-uebernahme-der-margon-arena-nach-C3IC74MZ6FE43AKGCZJSKUXA3I.html

In Firefox the content is cut off, in Edge it is displayed normally.

With Edge and Firefox 115.14.0esr the page is displayed normally. No AdBlock installed.

In developer mode I see the errors in the versions, so it shouldn't be that.

Cross-source (cross-origin) request blocked: The same-source rule prohibits reading the external resource on https://gum.criteo.com/sid/json?origi...AAAAAAAA&gdpr=1. (Reason: CORS request failed). Status code: (null).

Cross-source (cross-origin) request blocked: The same-source rule prohibits reading the external resource on https://id5-sync.com/api/config/prebid. (Reason: CORS request failed). Status code: (null).

Any ideas? Thank you very much! :)

Hello, For FF on Linux running in KIOSK mode, is there a way to allow the user to perform a refresh like you can do in normal mode by pressing F5 ? This seems to be disabled in KIOSK mode.

Thank you, Tom

Hi all

I like to enforce the following setting "Require device sign in to fill and mange passwords" in the mozilla.cfg but I couldn't find the setting in about:config.

Can anyone help?

Regards

Ogami

I am trying to use group policy to block all extensions from being installed and only allow approved extensions.

I have followed the article:

https://firefox-admin-docs.mozilla.org/reference/policies/extensionsettings/

And here is my JSON config but it doesnt seem to be working and I can still install any extension.

{

 "*": { 

"blocked_install_message": "Please email the IT Helpdesk if you think an extension should be unblocked.", "installation_mode": "blocked" }, "com.abr.startapp@adminbyrequest.com": { "installation_mode": "force_installed", "install_url": "https://addons.mozilla.org/firefox/downloads/latest/admin-by-request/latest.xpi" } }

Please can anyone advise or confirm if this is a bug.

We are using firefox version 147.0.4 (64-bit)

Thanks

Dear Community,

i had .cfg file with following settings to clean up some userdata after closing firefox:

//Clean UP Cache etc. lockPref("privacy.sanitize.sanitizeOnShutdown", true); lockPref("privacy.clearOnShutdown.cache", true); lockPref("privacy.clearOnShutdown.cookies", false); lockPref("privacy.clearOnShutdown.offlineApps", true); lockPref("privacy.clearOnShutdown.sessions", false);

This cleaned the "Storage" Folder in the Firefox Profile folder, but cookies and sessions where remaining, so the logins where active.

Now i saw that all useres have lots of folders in the "Storage/Default" folder. After some research i found out that this behavior startet at 02.10.2024.

I also found a new pref: privacy.clearOnShutdown_v2.cookiesAndStorage which was set to "false". No idea where this key came from? When I set this key to "Yes", the storage is cleared after closing Firefox. But so also all the cookies. Was there a change at the prefs?

And is ther any other solution to clear the Storage but remain the cookies?

Thank you in advance!

Dear Sir or Madam,

We are experiencing an issue with various users on our terminal servers whereby websites open very slowly when using Firefox. When I access the website using Edge from the same user session, everything works very quickly. We have already tried creating a new profile in Firefox and clearing the cache, but without success. Could you please help us?

The operating system used is Windows Server 2022.

Hello everyone,

We have been using Mozilla Firefox ESR (32-bit) in the organization for several years. For installation on our clients, we use "Matrix42 Empirum" as the software distribution tool. All it does is install the MSI of Firefox.

However, for quite some time now (almost 2 years), we have been facing an issue where some installations are marked as successful (Error code 0), but once the MSI installer is automatically closed, files like "firefox.exe" disappear from the installation directory – despite the installation being marked as successful.

The problem doesn’t always occur, but a repair attempt usually resolves the issue.

In addition to Empirum, we also use Defender for Endpoint, but we couldn’t find any clues there.

Is this problem known, or are we the only ones experiencing it?

Firefox is used on Windows 11 Enterprise. There is a firefox.cfg in the installation directory (and an autoconfig.js in the ./defaults/pref sub-directory). The firefox.cfg targets an autoconfigfile.js. This setup is recommended here: [firefox using autoconfig"]

1. In the support article´s example, the firefox.cfg uses a pref(); expression. Is it possible to use a lockPref(); expression instead?
2. What is the result of either using pref(); expressions or user_pref(); expressions in the remoted autoconfigfile.js? Are both of them possible, especially while the firefox.cfg uses lockPref(); expressions instead of pref();?

I hope that somesone can help with one of these questions. Thanks a lot!

Hello, Mozilla community.

I am trying to configure a Firefox ESR installation so that every new user on a computer automatically receives a visual customization (a logo change on about:home) through userChrome.css and userContent.css files.

My goal is to do this without using Group Policy (GPO) or logon scripts, by only modifying the files in the Firefox installation folder.

Environment:

Firefox Version: Firefox ESR 140.3.0esr

Operating System: Windows 11 Pro

Context: Standalone machine, managed without Active Directory.

My Question:

Is this method of deploying a default profile via installation files (defaults/profile or distribution.ini) still supported in recent versions of Firefox ESR?

Is there an additional step or configuration I am missing for Firefox to recognize and use the bundled profile when creating a user's first profile?

Is there any policy in policies.json that could be interfering or that is required to enable this behavior?

Thank you very much for your help and your time.

I've been tasked with removing Firefox from all Windows workstations in our enterprise environment. Our users don't have local admin, so when they install Firefox, it is installed in the user's profile.

I've just installed Firefox 143.0.1 in my own user profile for testing purposes. However, when I attempt to uninstall, either from Control Panel or by running %localappdata%\Mozilla Firefox\uninstall\helper.exe manually, UAC prompts for elevation, even though I installed without elevating.

Is this a known issue? If yes, is there a workaround?

Thanks!

Is there any parameter or group policy similar to Chrome "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome\AutoSelectCertificateForUrls]", as we implemented application with Certificate sign-in, it pop-up every time when navigating to different on-prem servers, we enabled Group policy for MSEdge & Chrome, but need to do same for Mozilla Firefox.

I need expert advice on this subject matter.

Regards,

Kamal Kiri