Firefox 84.0 Stable and Firefox ESR 78.6 will be released later today (if you are reading this on December 15, 2020). The new versions of the Firefox web browser will be distributed via the browser's automatic updating system and also as direct downloads from the Mozilla website.
All development versions of Firefox are updated as well to new versions. Firefox Beta and Firefox Developer are updated to version 85, Firefox Nightly to version 86. Firefox for Android follows the stable version's release scheme and will be upgraded to version 84.0 as well.
Firefox 84.0 is the last major release of 2020.
Check out the Firefox 83.0 release notes if you missed them.
Firefox 84.0 and Firefox 78.6 ESR upgrades are available via the automatic updating system and as standalone downloads. Firefox users may run manual checks for updates by selecting Menu > Help > About Firefox.
Firefox displays the installed version and runs a check for updates when the page is opened.
Manual downloads are also available. The following pages list direct downloads for supported Firefox channels (will be available later on December 15, 2020)
I reviewed this feature when it landed in Firefox Nightly in October, and you may want to check out the review for details.
Firefox extension developers may request optional permissions for extra functionality, e.g. when the user enables a new feature in the options. The problem up until now was that these optional permissions were not listed on the add-ons management page about:addons and users had no option to revoke optional permissions unless the extension author added such functionality to the extension.
Starting in Firefox 84, users may now manage optional permissions on about:addons. These permissions can be revoked directly from there. Note that revoking permissions may break certain functionality of the extension.
Mac users who run Firefox on devices with Apple Silicon CPUs may notice "dramatic performance improvements" compared to the non-native Firefox 83.0 build according to Mozilla.
The organization notes that Firefox's launch time has improved significantly (over 2.5 times faster compared to Firefox 83) and that web apps are "twice as responsive".
Mac users who upgrade to Firefox 84 need to fully close Firefox after installing the Firefox 84.0 upgrade to ensure that Firefox 84.0 runs on the new architecture; that this is the case can be verified by opening about:support and searching for "Rosetta Translated". If the value is false, the new architecture is used.
Two Mac OS issues are listed:
Security updates are revealed after the official release of the web browser. You find the information published here after release.
The Firefox 85.0 release date is January 26, 2021; this is the first version of Firefox without Adobe Flash support, or in fact, any NPAPI support.
Recently Reviewed Firefox extensions
New Section; we highlight reviews of Firefox add-ons since the last stable release of the browser here.
Additional information / sources
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