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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.

55.0a1 Firefox Nightly

March 6, 2017

Version 55.0a1, first offered to Nightly channel users on March 6, 2017

Firefox Nightly gets a new version 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.

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


  • Launched Windows support for WebVR, bringing immersive experiences to the web. See examples and try working demos at Mozilla VR.

    Bug 1218482
  • Simplified installation process with a streamlined Windows stub installer

    • Firefox for Windows 64-bit is now installed by default on 64-bit systems with at least 2GB of RAM
    • Full installers with advanced installation options are still available
    Bug 1365998
  • Updated Sidebar for bookmarks, history, and synced tabs so it can appear at the right edge of the window as well as the left

    Bug 1355331
  • Pages can be simplified before printing from within Print Preview

    Bug 1362526
  • Updated Firefox for OSX and macOS to allow users to assign custom keyboard shortcuts to Firefox menu items via System Preferences

    Bug 429824
  • All locales are now available for Nightly

    Bug 1355082
  • Browsing sessions with a high number of tabs are now restored in an instant

    Bug 1345090
  • The Photon project aiming at refreshing the user interface started being implemented in Nightly. These changes are only visible on the nightly channel and will not land in the beta and release channels before at least version 57.

    Bug 1346488
  • Fine-tune your browser performance from the Preferences/Options page.

    Bug 1364070
  • Make screenshots of webpages, and save them locally or upload them to the cloud. This feature will undergo A/B testing and will not be visible for some users.

    Bug 1356243
  • Search suggestions are now enabled by default for users who haven't explicitly opted-out

    Bug 1344928


  • Modernized application update UI to be less intrusive and more aligned with the rest of the browser. Only users who have not restarted their browser 8 days after downloading an update or users who opted out of automatic updates will see this change.

    Bug 893505
  • The default font for Japanese text is now Meiryo

    Bug 548311
  • Firefox does not support downgrades, even though this may have worked in past versions. Users who install Firefox 55+ and later downgrade to an earlier version may experience issues with Firefox.

    Bug 977177
  • Firefox uses Mozilla Location Service for geolocation

    Bug 1341897
  • about:preferences has been cleaned up and reorganized to make it easier for you to find what you need

    Bug 1335907
  • Made the Adobe Flash plugin click-to-activate by default and allowed only on http:// and https:// URL schemes. (This change will not be visible to all users immediately. For more information see the Firefox plugin roadmap)

    Bug 1317856


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