Firefox 94.0 release: here is what is new and changed

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

The new Firefox release marks the end of the Firefox 78 ESR branch, as it won't receive updates anymore. Firefox 91 ESR is the new and only branch that is supported by Mozilla.

All other Firefox channel editions 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 release overview here.

Executive Summary

Firefox 78 ESR is no longer support.
Firefox displays a Colorways prompt on first run, which allows users to pick a different color scheme.
Site Isolation is now enabled.
Firefox 94.0 includes security updates.

Firefox 94.0 download and update

firefox 94

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

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

Firefox 94.0 features and improvements

Seasonal Colorways

firefox colorways

Firefox displays a "pick your palette" overlay on first start after the upgrade to Firefox 94.0 or the new installation of the browser.

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

These new palettes can also be selected on the themes customization page of the browser.

Load about:addons
Switch to Themes.
Scroll down to the Colorways section.

There you find all available palettes, more than six, and the option to enable one of the available options in Firefox.

Note that the selection of a colorway will disable the active theme. You can switch back at any time by enabling the theme again.

Windows Background Updates

firefox windows background update

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 is unclear why it is mentioned again in the Firefox 94 release notes.

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

Load about:preferences in the Firefox address bar.
Scroll down to "Allow Firefox to" on the page.
Uncheck "Use a background service to install updates".

Site Isolation in Firefox Stable

Mozilla started to test Firefox's Site Isolation feature in Firefox 70, and rolled it out in Firefox Nightly in September 2020. Called Project Fission internally, site isolation aims to improve privacy and security significantly by isolation webpages and third-party iframes.

You can check out Mozilla's post here for additional details.

Site Isolation builds upon a new security architecture that extends current protection mechanisms by separating (web) content and loading each site in its own operating system process.

This new security architecture allows Firefox to completely separate code originating from different sites and, in turn, defend against malicious sites trying to access sensitive information from other sites you are visiting.

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 lets users 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 fullscreen video on YouTube and Twitch; this is done to extend battery life.
The page about:unloads 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 first-party URL of a cookie when it's in storage that is partitioned by top-level site, is added to cookies.get, cookies.getAll, cookies.set, cookies.remove, and cookies.cookie
New supported static method: HTMLScriptElement.supports().
New supported property: ShadowRoot.delegatesFocus.
@import rule supports the layout() function.

Enterprise changes

An MSIX is now provided for Firefox Stable. It is not yet provided for Firefox ESR.
Starting in Firefox 91 and Firefox 78.12, DisplayName in the uninstall data does not include the version anymore to "make it easier to write scripts that use this value".
Bugs in the policies DNSOverHTTPS and FirefoxHOME were fixed.

Bug Fixes

Performance improvements in various areas.
- We’ve reduced the overhead of using performance.mark() and performance.measure() APIs with a large set of performance entries.
- Plus, we’ve modified paint suppression during load to greatly improve warmload performance in Site Isolation mode.
- And we’ve improved pageload (especially with Site Isolation mode) by setting a higher priority for loading and displaying images.
- With this release, you’ll notice faster Javascript property enumeration as well.
- We’ve also implemented better scheduling of garbage collection which has improved some pageload benchmarks.
- Faster storage initialization.
- Cold startup improvement by reducing main thread I/O.
JavaScript memory reduction.
Reduced CPU usage during socket polling for HTTPS connections.
Closing the Developer Tools reclaims more memory.

Known Issues

None listed.

Security updates / fixes

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

Outlook

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

Recently Reviewed Firefox extensions

None.

Recent Firefox news and tips

Additional information / sources