Firefox 93.0 release: here is what is new and changed

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Firefox 93.0 will be released later today, if you are reading this on October 5, 2021. The new stable version of Mozilla's Firefox web browser is a feature update that includes security and stability fixes as well.

Executive Summary​

  • Firefox 78.15 ESR is the last release of the branch, and the only supported version of Firefox to support Adobe Flash and Mac OS X versions 10.11 and older.
  • Firefox supports the AVIF image format by default
  • WebRender should be enabled on all systems now.
  • Firefox 92.0 includes security updates.

New features and improvements​

AVIF format support is enabled by default

avif support


Mozilla planned to enable AVIF support in Firefox 92, but postponed the release. AVIF support is enabled by default in Firefox 93. It is an open format that offers "excellent compression" and has no patent restrictions.

The Firefox implementation supports still images, "with colorspace support for both full and limited range colors, and image transforms for mirroring and rotation", but no animated images.

Tip: open this test site in your browser to see if it supports AVIF.

Unload tabs on Windows when memory is critically low

Firefox includes a new tab unloading feature on Windows. It is an automated feature that will unload tabs if available "system memory is critically low".

Tabs are unloaded based on last access time, memory usage and other attributes.

Mozilla hopes that the feature will reduce the number of memory-related crashes that users of Firefox experience.

See our full coverage of Firefox's new tab unloading feature here..

Insecure downloads are blocked by default

firefox block insecure downloads


Firefox blocks insecure downloads by default now (non-secure downloads on secure webpages).

The preference dom.block_download_insecure can be toggled to allow insecure downloads again, by setting it to False.
  1. Load about:config in the Firefox address bar.
  2. Confirm that you will be careful if the warning prompt is displayed.
  3. Search for dom.block_download_insecure.
  4. Set the preference to FALSE.
See our full coverage of the new insecure downloads blocking feature of Firefox here.
 

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Firefox improves advertising tracker blocking in private browsing​

Mozilla says that Firefox users will be better protected from advertising trackers (like Google Analytics scripts) while browsing the Internet in Private Browsing mode and using Strict Tracking Protection.

This is because, starting with the Firefox 93 version released yesterday, the browser comes with improved web compatibility for privacy protections via SmartBlock 3.0.

The SmartBlock mechanism, introduced by Mozilla with the release of Firefox 87 in March, ensures that the Tracking Protection feature and Strict Mode don't break websites when blocking tracking scripts.

It does that by loading local and privacy-preserving alternatives to blocked resources with behavior similar enough to the original ones to ensure that the site still works properly.

"The third iteration of SmartBlock brings vastly improved support for replacing the popular Google Analytics scripts and added support for popular services such as Optimizely, Criteo, Amazon TAM and various Google advertising scripts," Mozilla said.

"As usual, these replacements are bundled with Firefox and can not track you in any way.

Starting with this release, Firefox also comes with enhanced Referrer Tracking Protection which blocks sites from sharing sensitive user data via HTTP referrers by trimming the HTTP referrer for cross-site requests, regardless of the site's settings.