Firefox Nightly
Release Notes

Release Notes tell you what’s new in Firefox. As always, we welcome your feedback. You can also file a bug in Bugzilla or see the system requirements of this release.

Firefox Nightly

April 6, 2020

Version 77.0a1, first offered to Nightly channel users on April 6, 2020

Firefox Nightly gets updated every day and as a consequence, the release notes for the Nightly channel are updated continuously to reflect features that have reached sufficient maturity to benefit from community feedback and bug reports.

Warning: Features listed here may or may not make a final release of Firefox.

In addition to these release notes, you can follow ongoing development on our @FirefoxNightly Twitter account as well as read our Nightly Blog.


  • The browser.urlbar.oneOffSearches preference has been removed. To hide one-off search buttons uncheck search engines on the about:preferences#search page

    Bug 1628926

Web Platform

  • Experimental AVIF support can be enabled by turning on image.avif.enabled in about:config. Images accessed via a file:// handler will be rendered in-browser, but remote URLs require the server to be configured to return the image/avif Content-Type header. contains a large number of properly-served sample images.

    Bug 1625363
All Firefox Nightly downloads