Firefox 66.0 will be released on March 19, 2019 to the Stable channel. The new Firefox version introduces new features such as sound autoplay blocking, a new storage format for extensions to improve performance, or support for the AV1 codec on Windows.
All versions of the web browser receive upgrades: Firefox Stable to version 66, Firefox Beta to version 67, Firefox Nightly to version 68, and Firefox ESR to 60.6.
Our release information guide offers detailed information. It covers major and minor changes, developer related changes, known issues, and security information.
Read up on the Firefox 65.0 release if you missed it.
The distribution of Firefox 66 starts today. Firefox users should receive update notifications automatically when they run the web browser.
Those who don't want to wait for the browser to pick up the update automatically, can run a manual update check or download the stable version from official sources to install it manually over the old version or anew.
Autoplaying audio is blocked by default
Mozilla Firefox 66 will block autoplaying (audible) sound on web pages that you visit. Mozilla plans to roll out the feature gradually starting with the release of Firefox 66.
Firefox users may whitelist sites to allow them to play autoplay media with sound.
You can enable or disable the feature, and manage exceptions in the following way:
Extensions switched to a different storage type to improve performance
One of the major changes in Firefox 66 is a change in how extension's store data in Firefox. The switch from JSON to IndexedDB should improve performance and reduce memory usage at the same time according to Mozilla.
Especially extensions that make "small changes to large structures", e.g. content blockers, benefit from the change.
The migration happens automatically in the background, user interaction is not required.
Security vulnerabilities and patches issues are revealed after the release. We will add a link once Mozilla publishes those.
The next stable release is Firefox 67, scheduled to be released May 14, 2019.
Additional information / sources
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