See what landed recently in Firefox Nightly!

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.

135.0a1 Firefox Nightly

November 25, 2024

Version 135.0a1, first offered to Nightly channel users on November 25, 2024

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 X account, our @FirefoxNightly Mastodon account as well as read our Nightly Blog.

You can interact with other Firefox Nightly users and give your feedback to Mozilla staff in the Nightly Matrix room on chat.mozilla.org.

New

  • Users on macOS and Linux are now given the option to close only the current tab if the Quit keyboard shortcut is used while multiple tabs are open in the window.

    Bug 1451132
  • Starting with Firefox Nightly 135, the DevTools toolbox colors have been updated to have higher contrast than the regular theme when in High Contrast Mode. Note that this change will only be activated when all of these conditions are met:

    • High Contrast Mode is enabled for the system.
    • In about:settings, in the Colors popup, Use system colors is checked, and Override the colors specified by the page with your selections above is set to something else than Never.
    • In DevTools settings, the selected Theme is Auto.
    Bug 1932642
  • Firefox now includes new safeguards to prevent sites from overwhelming the Back history by spamming numerous consecutive visits over a short time.

    Bug 1915404
  • To help Mozilla find and fix crashes, you can opt into automatically sharing Firefox for Android crash reports by checking the new Data Collection setting "Automatically submit crash reports".

    Bug 1812770
  • Starting with Firefox Nightly 134, Firefox can now selectively unblock certain social media embeds in ETP Strict or Private Browsing mode, allowing users to access blocked content without decreasing their overall protection level.

    Shield menu with the new smartblock option

    Instagram content marhed as blocked

    Bug 1920776

Changed

  • Starting with Firefox for Android 131, HLS playlist support was deprecated in Nightly builds. Extended testing showed no adverse impact as newer playback technologies have been widely adopted by websites.

    Bug 1911651
  • Starting with Firefox Nightly 135, macOS DMG packages now use LZMA for compression, reducing download size and installation time.

    Bug 1880009
  • The "Copy Without Site Tracking" menu item was renamed to "Copy Clean Link" to help clarify expectations around what the feature does. "Copy Clean Link" is a list based approach to remove known tracking parameters from links.

    Bug 1924493
  • Starting with Firefox 135, Linux binaries are now provided in XZ format, replacing the previous BZ2 format, offering faster unpacking and smaller file sizes. Blog Post

    Bug 1710599
  • Starting with Firefox Nightly 135, third-party tracking cookies are now protected by Total Cookie Protection instead of being blocked by default.

    Bug 1935156

Developer

  • Starting with Firefox 133, the Developer Tools debugger editor now uses Codemirror 6 in Firefox Nightly builds. Developer Tools debugger users should see performance improvements with larger files.

    Bug 1904489

Web Platform

  • Starting with Firefox 133, basic features of contenteditable="plaintext-only" are now supported in Firefox Nightly. Firefox still uses <br> elements for line breaks in contenteditable="plaintext-only" even when white-space is pre, pre-line, or pre-wrap. Therefore, textContent of editing host returns one line text even if there are multiple lines.

    Bug 1922723
  • Starting in Firefox 135, Nightly builds now send a referrer from meta refreshes and Refresh headers, improving compatibility with sites such as Twitch.

    Bug 1928290
  • Starting with Firefox 135, the Temporal proposal, a better version of Date, is now available for experimentation in Nightly builds behind the javascript.options.experimental.temporal preference. For more details, see https://tc39.es/proposal-temporal/docs/.

    Bug 1912757

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