Forum der Gemeinschaft Firefox Enterprise

Hi,

I'm having a performance issue with Firefox on my computer. After Firefox has been running for a while, it sometimes becomes noticeably slower when I use several browser-based tools and keep multiple tabs open.

For example, I noticed it while using an online one rep max calculator to work out estimated lifting numbers. The calculator itself is fairly simple, but Firefox occasionally starts using more CPU and the browser feels less responsive.

I have several extensions installed, so I'm not sure whether an extension, a particular tab, or Firefox itself is responsible.

I've already tried closing unnecessary tabs, but the problem can still come back.

Is there a good way to determine whether a Firefox extension is causing the high CPU usage? Would checking about:processes or running Firefox in Troubleshoot Mode be the best way to narrow it down?

I'm especially interested in knowing how to identify the specific extension or tab responsible rather than disabling everything permanently.

Thanks.

Hi

We are managing Firefox settings using Intune and successfully imported the Mozilla/Firefox ADMX files. A few settings are working as expected on a test device, though we're encountering issues with the Extension Management policy.

We followed this documentation to set up the extension management json: https://firefox-admin-docs.mozilla.org/reference/policies/extensionsettings/. I can see the policy is loaded into Firefox, though I am unable to add uBlock Origin, which should be allowed. All extensions are blocked, and the custom error message does not appear either, but instead "Download failed. Please check your connection."

I've tried a few variations with mixed success, but I haven't been able to get "allowed" extensions to work. Force installed extensions seem to work just fine.

Here's a minimal policies.json that demonstrates the issue:

{

   "*": {
       "blocked_install_message": "Custom error message.",
       "installation_mode": "blocked"
   },
   "uBlock0@raymondhill.net": {
       "installation_mode": "allowed"
   }

}

Is there something I'm missing? The test device is running Firefox 156.0.1 64-bit, firefox.admx 8.3, mozilla.admx 4.8. Any help or suggestions would be greatly appreciated! Thanks.

We are evaluating Mozilla Firefox/Firefox ESR as a temporary workaround for an enterprise application that currently depends on XSLT. Our application is expected to be upgraded by the end of February 2027, after which the XSLT dependency will no longer be required. We understand that Mozilla is investigating the deprecation/removal of XSLT from Firefox, but we have not found a confirmed removal date.

Could you please confirm: Is there a planned Firefox or Firefox ESR release in which XSLT will be disabled or removed? Can you confirm whether XSLT is expected to remain supported through February 2027? If removal is planned, which Firefox/ESR version is expected to remove it? Does Firefox ESR provide any additional guarantee or extended support for XSLT? Is there an official Mozilla roadmap or documentation that we can reference for our enterprise planning?

This information is important because we have approximately 5,000 users who may be affected, and we need to determine whether Firefox can safely be used as a temporary workaround until our application upgrade.

Dear Firefox Support Team,

We are evaluating the deployment of Mozilla Firefox Group Policy templates in our organization to support Microsoft Defender for Endpoint Network Protection.

Microsoft has advised us that, for custom URL/domain Indicators to work correctly in Firefox, we need to:

1. Download the Firefox policy templates from:

  https://github.com/mozilla/policy-templates/releases

2. Copy the files and folders under the Windows directory to:

  `C:\Windows\PolicyDefinitions`

3. Enable the **Disable Encrypted Client Hello** policy.

4. Configure the following preference to disable HTTP/3:

```json {

 "network.http.http3.enable": {
   "Value": false,
   "Status": "default"
 }

} ```

Microsoft referred us to Mozilla for clarification regarding the lifecycle, compatibility and rollback of the Firefox policy templates. Before deploying the configuration across our managed Windows devices, we would appreciate your guidance on the following questions.

1. Policy template update frequency

We noticed that new versions of the Firefox policy templates are released quite frequently.

• Is it necessary to deploy every new version of the policy templates?
• Should organizations establish a regular schedule for updating the ADMX/ADML files?
• Alternatively, should the templates only be updated when a required policy has changed or when the installed Firefox version requires a newer template?
• Is there a recommended method for matching a policy-template version with Firefox Release and Firefox ESR versions?
• Could an older policy-template version continue to be used if it already contains the required policies?

2. Different Firefox versions across endpoints

Our users may have different versions of Firefox or Firefox ESR installed.

If the same policy templates and settings are deployed to all managed Windows devices:

• What happens when an installed Firefox version does not support a setting included in the policy template?
• Will Firefox simply ignore an unsupported policy, or could it cause policy-processing errors or browser compatibility issues?
• Is there a minimum supported Firefox or Firefox ESR version for `DisableEncryptedClientHello` and the `network.http.http3.enable` preference?
• Do you recommend targeting the deployment according to the installed Firefox version?

3. Devices without Firefox installed

Some managed devices do not have Firefox installed.

• Is it safe to deploy the Firefox ADMX/ADML files and related registry-based policy settings to those devices?
• Will the files and settings remain inactive until Firefox is installed?
• Could deploying the templates or registry settings have any effect on Windows or other browsers?

4. Replacement of existing templates

When copying the files into `C:\Windows\PolicyDefinitions`, Windows may prompt us to replace existing Mozilla ADMX/ADML files.

• Is it safe to replace older versions with the latest released templates?
• Could replacement affect or remove existing Firefox Group Policy configurations?
• Should the existing files be backed up before replacement?
• Do we only need `mozilla.admx`, `firefox.admx` and the corresponding language-specific ADML files, or should every file and language folder in the Windows package be copied?

5. Rollback procedure

If the deployment causes an unexpected browser, compatibility or performance issue, what is Mozilla’s recommended rollback procedure?

Should we:

• Change **Disable Encrypted Client Hello** to *Not Configured* or *Disabled*;
• Remove or reverse the `network.http.http3.enable` preference;
• Remove the associated Firefox policy registry values;
• Restore the previous ADMX/ADML files; and/or
• Remove the current templates from `C:\Windows\PolicyDefinitions`?

Please clarify whether withdrawing the Group Policy assignment is sufficient to restore Firefox’s default ECH and HTTP/3 behavior, or whether endpoint-level cleanup is also required.

6. Recommended enterprise deployment approach

For a managed enterprise environment, would Mozilla recommend deploying these templates through:

• The Active Directory Group Policy Central Store;
• Local `C:\Windows\PolicyDefinitions`;
• Microsoft Intune ADMX ingestion;
• Direct registry-based policies; or
• Another supported method?

We would appreciate Mozilla’s official recommendation so that we can complete our internal risk assessment and prepare an appropriate deployment, maintenance and rollback plan.

Thank you for your assistance.

Best regards, Summer

Hello Firefox Support,

I would like to report a reproducible video playback problem in Firefox on Windows 11. I have already spent considerable time troubleshooting it, including testing Firefox graphics and video related settings and ultimately performing a completely clean reinstall of Firefox. The problem persists after the clean installation.

My system configuration is: Device name: Mephisto PC Operating system: Windows 11 Pro for Workstations, 64 bit Windows version: 25H2 OS build: 26200.9457 Windows Feature Experience Pack: 1000.26100.360.0 Processor: AMD Ryzen 7 9700X 8 Core Processor, 3.80 GHz Installed RAM: 32.0 GB, 31.1 GB usable Graphics card: AMD Radeon RX 7800 XT, 16 GB VRAM Integrated graphics: AMD Radeon(TM) Graphics, 486 MB System type: 64 bit operating system, x64 based processor The primary discrete GPU used by the system is the AMD Radeon RX 7800 XT

The problem appeared suddenly. Firefox had been playing videos normally the previous day. As far as I am aware, neither Firefox nor the AMD graphics driver had been updated immediately before the problem appeared.

The symptom is severe video stuttering during playback in Firefox. The video is not merely dropping an occasional frame. Playback becomes visibly and consistently jerky rather than smooth. The most important finding is that I have been able to isolate the problem specifically to Firefox's hardware video decoding.

In about:config, I changed: media.hardware-video-decoding.enabled from: true to: false With hardware video decoding disabled, video playback immediately becomes smooth and continuous. If hardware video decoding is enabled again, the stuttering returns. This is currently the only workaround I have found that reliably eliminates the problem.

I also tested Firefox's DirectComposition hardware video overlay setting: gfx.webrender.dcomp-video-hw-overlay-win Setting this to false did NOT solve the problem. Video playback continued to stutter.

I investigated the related DirectComposition/WebRender video overlay preferences as part of the troubleshooting process as well, but disabling the hardware video overlay did not reproduce the improvement obtained by disabling hardware video decoding itself.

I then decided to rule out corruption of the Firefox installation or profile. I performed a complete, clean Firefox reinstallation. After reinstalling Firefox from scratch, the exact same problem remains. Therefore, the behaviour is reproducible on a clean Firefox installation.

The important observations can be summarized as follows: Firefox with hardware video decoding enabled: video stutters severely. Firefox with media.hardware-video-decoding.enabled = false: video playback is smooth. Firefox with gfx.webrender.dcomp-video-hw-overlay-win = false: video still stutters. Completely clean Firefox reinstall: problem still occurs.

The PC itself has not changed hardware, and the problem appeared despite Firefox having worked correctly on the same machine previously.

Given these results, this appears to involve Firefox's hardware accelerated video decoding path and its interaction with the AMD Radeon RX 7800 XT, the AMD graphics driver, Windows 11 video acceleration, or some combination of these components, rather than ordinary Firefox profile corruption.

Disabling hardware video decoding is a functional workaround, but I do not consider it an ideal permanent solution on a modern GPU which is specifically designed to provide hardware accelerated video decoding. I would therefore appreciate assistance in determining why Firefox's hardware video decoder has suddenly begun producing severe stuttering on this system.

If useful for diagnosis, I can provide additional technical information from about:support, including Graphics, Media, WebRender, hardware video decoding, codec and driver information. I can also perform specific diagnostic tests if you tell me exactly what information is required.

Thank you.

I am using Ubuntu Linux on a desktop PC running Firefox in kiosk mode going to a specific web page - Every time Firefox does an update (since version 147) the kiosk mode stops working. The very latest update, after a reboot, just shows the menu bars and not Firefox going to that specified web page. Has the kiosk code changed since v147 ?

I have Mozilla Firefox and Mozilla ESR browsers updates to manage across the devices. Policies have been configured on browser from Intune and same has been reflected everywhere in registry, and update.json file. still task is missing. can someone help on this. Also i have few ESR so will same ADMX file will work for that?

Hi all,

We use a service integration in our organization that only works in the latest ESR version of Firefox (140.14). The latest regular release breaks our integration due to added security policies preventing the software from communicating with Windows services.

After installing the ESR version and disabling auto updates in the settings and adding the DisableAppUpdate registry key, the software still keeps updating to 154 (not the ESR version). I've also chosen to not install the Mozilla Maintenance service when installing the ESR version. I can't seem to find any support articles of people having the same issue. Is there something I may be missing? Any help would be greatly appreciated.

Hello, we have the issue, that Firefox esr 153.1.0 crashes on opening urls. The crashes happen on several devices. These are the current crash-reports: bp-3e6bd41b-89b0-4a49-9479-90cbc0260831 bp-9bd858e0-2573-4a01-8bac-90c320260831 bp-ad358921-a24d-4e02-9ed5-2bc4d0260831 bp-0bfb15d0-b637-48b6-a445-94b350260831 bp-0dc0dbcb-fb77-4ce6-a1c0-659f40260831 bp-268bf05a-3eb7-493e-bd40-42e0c0260831 bp-3910ddb1-9dbd-4016-b421-0dd450260831

thanks for Help and advice.

Best Regards

Felix

Hi,

In the latest firefox update 154, no start pages are displayed that were distributed with a registry key via group policy. It only works again if you change this setting manually in the Firefox settings.

In Version 153 it´s fine.

Jan

Hallo, my setup is some server (keycloak) with mTLS needing keypairs just for allowance for the machines in the enterprise. But as far as i know, i need to setup personal keypairs for the users, not just the machines. How do i push a ".p12" keypair into the browsers trust stores? Is there a way via GPOs? As far as i have read the https://firefox-admin-docs.mozilla.org/reference/policies/, there is no support for ".p12" files?

The only way i got told from AI is via a script. If i could just stuff that ".p12" file into some place in the GPO, i would be perfectly happy... (?)

I don't understand why auto:config is so difficult (for me at least) to create. Isn't there an easier way? I've tried following the directions and creating the 2 files. But I can't manage to successfully create auto:config.

I created and pasted the first tile into the prefs folder. For the 2nd, I noticed the firefox.cfg file I created in Notepad appended a .txt suffix. I pasted it into the Firefox top directory. Then typed auto:config into the address bar. Nothing happened. Can anyone tell what I did wrong? Is the .txt suffix not recognized? Or is there's an easier way to do this?

We are managing Firefox settings using Intune via Imported ADMX templates.

We are managing Extension Settings via 'Extension Management (JSON on one line)' which works fine for our force installs, force removals etc.

We have noticed that some users have installed 3rd party extensions which create the ExtensionSettings key in the registry with the 3rd party extension details.

The issue we see if when ExtensionSettings exists as a REG_SZ or REG_MULTI_SZ under `HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox` it is then ignored if the `HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox\ExtensionSettings` key exists.

Is there a setting we can use to have these settings merged by Firefox or have the REG_SZ/REG_MULTI_SZ take priority or is the only way to ensure enterprise policy continues to work we need to migrate our extension settings into the key rather than string?

Thanks!

I'm trying to get the Enterprise Release Notes for Firefox 148 and 149. They seem to be the only ones missing from 141 to 151 inclusive. It appears the URL for the notes is in the format https://support.mozilla.org/en-US/kb/firefox-enterprise-###-release-notes/, where ### is the version. For these two versions, I get a "Page Not Found" error.

I have tried finding them through the Firefox Release Calendar (https://whattrainisitnow.com/calendar/). If you click on the link to expand previous releases and then click on a release version number, the page that comes up has links to the three different versions of release notes. Enterprise shows a link for the two missing versions in the same format as I have noted above.

I have also tried https://support.mozilla.org/en-US/products/firefox-enterprise/whats-new-firefox-enterprise and it lists quite a few versions but 148 and 149 are missing in action.