Firefox Enterprise Community Forum

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.

I've dug in a bit more, and I found this was an issue five years ago as well:

https://support.mozilla.org/en-US/questions/1286070

According to that post, the issue was resolved, but it seems to have come back.

Any help would be appreciated.

How to disable Firefox add-ons in order to block to install temporary extensions. I am generating policies via Firefox Policy generator. {

 "name": "myconfig",
 "time": "2025-12-14T13:17:27.479Z",
 "configuration": {
   "arrayfields": {},
   "checkboxes": {
     "BlockAboutAddons": true,
     "BlockAboutConfig": true,
     "BlockAboutProfiles": true
   },
   "input": {},
   "textareas": {},
   "select": {}
 }

}

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.

I've been struggling for months to standardize a deployment of Firefox ESR across various client environments that reliably auto-updates and doesn't cause UAC prompts and XULRunner profile error pop-ups(I work in IT).

We deploy Firefox ESR in bulk on machines via a batch script which runs as SYSTEM, with msiexec /i and /qn flags.

Firefox installs fine, but then users are typically met with a UAC prompt when they first try to run Firefox. If they decline, then the UAC prompt comes back again next time and often fails to update at all, so the machine is left on an older, vulnerable version.

Regarding the environment: we have deployed the Firefox ESR admx templates and enabled the relevant auto update settings in Group Policy. But only some machines seem to stay up to date, and it seems like this only happens if a user with local administrative privileges has run the program at least once.

What I find unusual is that Firefox seems to attempt to make a "Background Updater" scheduled task for every user that runs the software on each PC, but these users do not have administrative privileges, and the scheduled task is set to only run when that user is logged in. Obviously a scheduled task running as a user with limited privileges isn't going to be able to update files in the Mozilla/Firefox subdirectory in "Program Files" as by default that's read-only access for non-admin users. And, obviously, if a user with local admin privileges DOES log into the machine, then it can update once, but then the scheduled task that it creates for that user (now with admin privileges) will only run when that user logs in - and we don't login as "admin"-privileged users day-to-day.

So, various machines are out of date, running vulnerable Firefox 128 instead of 140 or 142 even though they're all deployed from the same image and have the same policies and restrictions, and ran the same installer for Firefox.

Is there some reason why the auto update scheduled task isn't created at installation time, when administrative privileges have been granted? It's very odd that it doesn't, because then every time a user logs into a machine it seems like Firefox ESR creates the background upgrade task under a non-admin user which simply won't work. I see machines having 4 or 5 background upgrade scheduled tasks, all created by Firefox ESR, and yet the software still won't update - there's a UAC prompt every time the program launches, and going to Help -> About shows "Restart Firefox to update..." but then when clicking the button to restart Firefox, we get the UAC prompt, user doesn't have privileges, so this goes around and around in circles.

Is there a reliable way to keep Firefox up to date without manually logging into each machine and going through the UAC prompts? Can we manually create a scheduled task with the correct user account that has privileges to actually upgrade Firefox?

The background auto update mechanism simply doesn't make sense to our team on a machine-wide install.

I previously posted this question: https://support.mozilla.org/en-US/questions/1495577

Asking how to use the "intl.accept_languages" setting within the JSON for the new preferences setting within group policy.

A moderator posted this as a comment which I have only just noticed: "The value is a string, so it has to be in quotes "en-GB"" - the post is now too old for me to reply.

I'm still having issues using this setting even after putting the name in quotes. I've tried:

"intl.accept_languages": { "Value": "en-GB", "Status": "user" }

"intl.accept.languages": { "Value": "en-GB", "Status": "user" }

But neither work, please can someone clarify what exactly needs to be used within the JSON?

I wanna thx for having Mozilla Firefox and i wanna ask about products for example with commercial versions but available for non profit organization in eastern EU area with social background. Im ask because afraid from local little old soft/dev gave as gift decade ago vs "confusing" logs etc?

I would like to know how the Firefox CVEs are affected on its version which are mentioned in NVD.

Let take mfsa2025-59, for example CVE-2025-8040, as per the NVD its says Firefox ESR < 140.1 is affected so does that mean it affect all the version which are lower than 140.1 which included the ESR 128 and ESR 115 versions or just the ESR 140 version series? then it raise on more question check this cve-2025-8029 in NVD it has specifically mentioned it only affect "Firefox ESR < 128.13, Firefox ESR < 140.1" and not the ESR 115 versions. Could anyone confirm it does not affect the ESR 115 versions or it affect all the versions? Now check this one cve-2025-8027, NVD clearly mentioned "Firefox ESR < 115.26, Firefox ESR < 128.13, Firefox ESR < 140.1" are affected so what I understand is that if the Firefox ESR 115 is vulnerable to any CVE it would be mentioned in the NVD specifically.

My point is that if any Firefox CVEs are listed in NVD and it specify only one version like “Firefox ESR < 140.1” what does that mean? Does it affect all the versions which include ESR 128 and ESR 115 or just the ESR 140 series version only affected? If any CVEs are affected on the ESR 115 and ESR 128 does Mozilla specifically mentioned those versions are affected right? Just like its mentioned in the cve-2025-8027

Any help would be appreciated to clarify this.

I am working on a stig for Mozilla Firefox and I'm trying to do a scap compliance scan but or some reason I am getting a score of zero on all systems. We do patch regularly and at some point one of the version upgrades caused our compliance scans stopped working. I need a fix and cannot find anything when searching for this issue.

GNU nano 8.6 /etc/firefox/policies.json {

 "policies": {
   "DisableFirefoxStudies": true,
   "DisableTelemetry": true,
   "DisableSystemAddonUpdate": true

   "Preferences": {
     "app.normandy.enabled": false,
     "app.shield.optoutstudies.enabled": false,
     "extensions.autoDisableScopes": 15
    }
  }
} Hidden modifications to settings and extensions is absolutely not OK!!!!!!

This is a security environment.

Greetings!

I am using the firefox enterprise version and I have noticed an issue that the browser does not capture mouse events when the pointer is at rightmost edge of the firefox window. For example, on this website near the edge the pointer would initially focus on the scroll bar and then lose focus at the edge (see attached images).

This issue does not persist on x11, and only seems to exist on wayland. It also exists on other flavours of firefox on wayland.

If more information is required, feel free to send me a ping.

I am logged on to my Credit Union and attempt to download my statements. When using Firefox I get the message: {"Errors":["Authorization has been denied for this request."]}

When I contacted my CU, they said to add an URL to the Manage Exceptions. This worked, but I want to know why Firefox needs this but Chrome doesn't.

Hello,

I had issue to verify the cert on android app for https://partners-enrichment.heytelecom.be. On Windows I didn't have the same issue.

version 144.0.2 / build id 20251027123126 / target arm64-v8a armeabi-v7a x86_64 Device: Samsung S22 / One UI 7.0 / Android version 15 / version S901U1UES8FYI2 / Security patch level September 1, 2025

Error: Secure Connection Failed, because its certificate issuer is unknown, the certificate is self-signed, or the server is not sending the correct intermediate certificates.

CertChain RCA: DigiCert Global Root G2 DCA: DigiCert Global G2 TLS RSA SHA256 2020 CA1 cert: partners-enrichment.heytelecom.be

1) I couldn't check the cert from the gui as on windows. Shield in search bar / Connection not secure doesn't opened the cert. Is it expected?

2) I found this helppage: https://support.mozilla.org/en-US/kb/setting-certificate-authorities-firefox

Unfortunately about:preferences isn't available on android (ref. https://www.reddit.com/r/firefox/comments/u593x0/how_to_access_to_aboutpreferences_on_android/)

I see in about:certificate which is the correct RCA (I verified the pem file with the root). DigiCert Global Root G2

Where do I check the Intermediate CA's (DCA)?

3) When exporting the RCA it has been download as: digicert-global-root-g2.pem.txt Why the txt at the end?

On Windows it downloads as digicert-global-root-g2.pem

Kind regards,

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?

I want nothing to do with AI.

I have unticked perplexity.ai in preferences#search but every search from the search bar and address bar goes to perplexity.ai then immediately crashes and displays "Internal Error".

To use DDG I have to type duckduckgo.com on the address bar then search from there.

Firefox 140.4.0 ESR.

I've' scanned the PC with malwarebytes. I restored windows from a backup image I haven't made any changes to the PC at all. Was working fine in the AM but by later afternoon, it started using perplexity.ai exclusively.

How do I get rid of perplexity.ai

I look after about 20 PCs. All Windows 10. All were running Firefox ESR ranging from 115 - 128. As I get time I update each to the latest 128.x. Using group policies I've disabled all update settings.

However, on two of the PCs, they have updated to v139.0.1. Both of the users swear they did not manually do any update. I can't figure out how they got downgraded to the retail channel.

So my question is, since 128 < 139 how can I get them back on to the ESR channel, without loosing history, bookmarks, passwords and saved logins? I gather FF's installer will detect 128 as an older version and throw an error?

ESR -> Retail to me is a downgrade. So is it possible then to upgrade back to 128.11.x?

Each PC is refreshed annually and the only backup of the profile folder I have is from the last refresh, which in most cases in 8-9 months old.

Is there any way to find out why the downgrade happened when group policy forbids it, and the user did not manually download and install the latest version?

When these downgrades happen they break things. For example, when one PC was downgraded to retail his outlook.com email no longer works. If he uses his laptop which is on 128.11.0 it works fine.

Hi,

I have 2 machines (Win10 and Win11) with FF 140.3.1esr (32-bit) installed which demonstrates the same failure when I enter one site's url:

PR_CONNECT_RESET_ERROR

Chrome at the same machines goes at this url w/o any failures. Any ideas what to change on "about:config" in FF to allow it opening this url w/o such error?