Firefox 94.0 version: here are the new features and changes

The release date of Firefox 94.0 is November 2, 2021. The new stable version of the Mozilla Firefox web browser introduces new features, bug fixes and security fixes.

The new version of Firefox marks the end of the Firefox 78 ESR branch, as it will no longer receive updates. Firefox 91 ESR is the new and only branch supported by Mozilla.

All other editions of the Firefox channel are updated at the same time. Firefox Beta and Developer editions are upgraded to Firefox 95, Firefox Nightly is upgraded to Firefox 96, and Firefox for Android to Firefox 94. Firefox 91.3 ESR is the new Extended Support Release version of the Firefox web browser.

Check out the Firefox 93.0 version overview here.


  • Firefox 78 ESR is no longer supported.
  • Firefox displays a Colorways prompt on first run, allowing users to choose a different color scheme.
  • Site isolation is now enabled.
  • Firefox 94.0 includes security updates.

Firefox 94.0 Download and Update

Mozilla Firefox 94.0 is automatically pushed to all stable versions of Firefox, provided the automatic update feature has not been disabled.

Firefox users can check the installed version and run a manual check for updates. Simply select Menu> Help> About Firefox to view the installed version. Firefox queries Mozilla servers for information about updates and will automatically download new updates.

Firefox 94.0 Features and Improvements

Seasonal colors

color firefox

Firefox displays a “choose your palette” overlay on first start after upgrading to Firefox 94.0 or new browser installation.

Called Colorways, Firefox users can select one of six seasonal color palettes for the browser or skip customization by selecting “keep previous theme”.

These new palettes can also be selected on the browser’s theme personalization page.

  1. Upload about: addons
  2. Switch to Themes.
  3. Scroll down to the Colorways section.

There you will find all the available palettes, more than six, and the possibility of activating one of the options available in Firefox.

Note that selecting a color will disable the active theme. You can come back at any time by activating the theme again.

Windows background updates

update firefox windows background

On Windows, updates are now handled automatically in the background using a background agent. Mozilla mentioned the feature in the Firefox 90 release notes, and it’s unclear why it is mentioned again in the Firefox 94 release notes.

The agent runs a task in Windows Task Scheduler called Firefox Background Update. You can delete or disable the task, but it may be better to disable the option in Firefox preferences.

  1. Load about: preferences in the Firefox address bar.
  2. Scroll down to “Allow Firefox to” on the page.
  3. Uncheck “Use background service to install updates”.

Site isolation in Firefox stable

Mozilla began testing Firefox’s Site Isolation feature in Firefox 70 and deployed it to Firefox Nightly in September 2020. Called Project Fission internally, Site Isolation aims to dramatically improve privacy and security by isolating third party web pages and iframes.

You can see Mozilla’s post here for more details.

Site isolation is based on a new security architecture that extends current protection mechanisms by separating (web) content and loading each site into its own operating system process.

This new security architecture allows Firefox to completely separate code from different sites and, in turn, defend against malicious sites that attempt to access sensitive information from other sites you visit.

Firefox Multi-Account Containers extension with Mozilla VPN integration

The latest version of Mozilla’s Firefox Multi-Account Containers extension introduces support for Mozilla’s VPN service. In particular, it allows users to use a different server location for each of the existing containers.

Other changes

firefox unload tabs

  • Firefox macOS now uses Apple’s low power mode for full screen videos on YouTube and Twitch; this is done to extend the battery life.
  • The about: unloads page is now available. It can be used to unload tabs manually to free up system resources.
  • Firefox no longer warns users that multiple tabs are open when the browser is closed (with one exception).
  • Firefox supports Windows 11 Snap layouts.

Developer changes

  • Support for partitionKey, the URL that owns a cookie when stored and partitioned by top-level site, is added to cookies.get, cookies.getAll, cookies.set, cookies.remove, and cookies.cookie
  • New static method supported: HTMLScriptElement.supports ().
  • New supported property: ShadowRoot.delegatesFocus.
  • The @import rule supports the layout () function.

Company changes

  • An MSIX is now provided for Firefox Stable. It is not yet provided for Firefox ESR.
  • Starting with Firefox 91 and Firefox 78.12, DisplayName in the uninstall data no longer includes the version to “make it easier to write scripts using this value”.
  • Bugs in DNSOverHTTPS and FirefoxHOME policies have been fixed.

Bug fixes

  • Performance improvements in various areas.
    • We have reduced the overhead of using the performance.mark () and performance.measure () APIs with a large number of performance entries.
    • Additionally, we have changed the paint removal while charging to significantly improve hot charging performance in site isolation mode.
    • And we’ve improved page loading (especially with site isolation mode) by setting a higher priority for loading and viewing images.
    • With this release, you will also notice faster enumeration of JavaScript properties.
    • We’ve also implemented better garbage collection scheduling, which has improved some page load guidelines.
    • Faster initialization of storage.
    • Improved cold start by reducing main thread I / O.
  • Reduced JavaScript memory.
  • Reduced CPU usage when polling sockets for HTTPS connections.
  • Closing developer tools reclaims more memory.

Known issues

None listed.

Security Updates / Patches

Security updates are revealed after the official release of the web browser. You will find the information published here after its publication.


Firefox 95.0 Stable will be released on December 7, 2021. Firefox ESR 91.4 will be released at the same time. This is the last major Firefox release of 2021.

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Additional information / sources


Firefox 94.0 version: here are the new features and changes

Article name

Firefox 94.0 version: here are the new features and changes

The description

The release date of Firefox 94.0 is November 2, 2021. The new stable version of the Mozilla Firefox web browser introduces new features and fixes bugs.


Martin Brinkmann


Ghacks Technology News



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