Firefox Release Notes

Firefox Home (the default New Tab) now allows users to display up to 4 rows of top sites, Pocket stories, and highlights

“Reopen in Container” tab menu option appears for users with Containers that lets them choose to reopen a tab in a different container

In advance of removing all trust for Symantec-issued certificates in Firefox 63, a preference was added that allows users to distrust certificates issued by Symantec. To use this preference, go to about:config in the address bar and set the preference "security.pki.distrust_ca_policy" to 2.

Added FreeBSD support for WebAuthn

Improved graphics rendering for Windows users without accelerated hardware using Parallel-Off-Main-Thread Painting

Support for CSS Shapes, allowing for richer web page layouts. This goes hand in hand with a brand new Shape Path Editor in the CSS inspector.

CSS Variable Fonts (OpenType Font Variations) support, which makes it possible to create beautiful typography with a single font file

Updates for enterprise environments:

• AutoConfig is sandboxed to the documented API by default. You
  can disable the sandbox by setting the preference
  general.config.sandbox_enabled to false. Our long term plan is to
  remove the ability to turn off the sandboxing. If you need to
  continue to use more complex AutoConfig scripts, you will need to use
  Firefox Extended Support Release (ESR).

Added Canadian English (en-CA) locale

Various security fixes

Removed the description field for bookmarks. Users who have stored descriptions using the field may wish to export these descriptions as html or json files, as they will be removed in a future release.

Dark theme is automatically enabled in macOS 10.14 dark mode

Changed the default setting to Enforce (3) for the security.pki.name_matching_mode preference

Adobe Flash applets now run in a more secure mode using process sandboxing on macOS. Learn how this may affect features here.

Users disconnecting from Sync are now offered the option to wipe their Firefox profile data (including bookmarks, passwords, history, cookies, and site data) from their desktop computer

Changed how WebRTC handles screen sharing: When screen-sharing a window, the window will be brought to front

Three-pane Inspector in Developer Tools separates the rules into its own panel

Changes affecting developers

Unvisited bookmarks will not be autofilled in the address bar (bug 1488879)

File management can fail on macOS Mojave (10.14) (bug 1489785)