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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.

124.0a1 Firefox Nightly

January 22, 2024

Version 124.0a1, first offered to Nightly channel users on January 22, 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 Twitter account, our 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


  • Starting with Firefox 122, the URL Paste Suggestion feature is now enabled by default in Nightly builds. This enhancement provides a convenient way for users to quickly visit URLs copied to the clipboard in the address bar of desktop Firefox. When the clipboard contains a URL, and the user focuses on the URL bar, an autocomplete result appears automatically. Activating the clipboard suggestion will navigate the user to the URL with 1 click.

    Bug 1860548
  • Starting with Firefox 122, scroll animations triggered using a mouse wheel or using the keyboard (e.g. arrow keys, Page Down/Up) are now based on a Mass-Spring-Damper physics model in Nightly builds, this gives animations a more realistic feel.

    Bug 1846935
  • Starting with Firefox 122, it is now possible to highlight information in the Firefox PDF viewer in Nightly builds.

    Bug 1867512
  • Firefox for Android now supports HTML drag and drop API when using a mouse. Also, it accepts plain text or HTML text by the drop operation from external applications.

    Bug 1586471
  • Starting with Firefox 124, Firefox now prompts nightly users in the US and Canada to save their addresses upon submitting an address form, allowing Firefox to autofill stored address information in the future.

    Bug 1875253
  • Starting with Firefox 124, Nightly users can now search in the Address Bar for tabs open in different containers. This behavior can be controlled through the browser.urlbar.switchTabs.searchAllContainers boolean preference.

    Bug 1876743
  • Caret browsing mode now also works in the PDF viewer. (Learn more)

    Bug 807730
  • Starting with Firefox 124, a simpler and more unified dialog for clearing user data is now available in Nightly builds. In addition to streamlining data categories, the new dialog also provides insights into the site data size corresponding to the selected time range.

    Bug 1874702
  • Firefox on Mac now uses the macOS fullscreen API for all types of fullscreen windows. This should better match the expected macOS user experience for fullscreen spaces, menubar and the Dock. Users who would like to return to the previous behavior should set the deprecated full-screen-api.macos-native-full-screen pref to false.

    Bug 1862223

Web Platform

  • Starting with Firefox 122, the popover attribute is now supported by default in Nightly builds. The popover global attribute is used to designate an element as a popover element. The element won't render until it becomes shown, it will then render on top of other page content.

    Bug 1866666
  • Starting with Firefox 122, the remaining part of the async clipboard API has been enabled by default in Nightly builds. A paste context menu will appear for the user to confirm when attempting to read clipboard data not provided by the same-origin page.

    Bug 1809106
  • Starting with Firefox 122, Nightly builds include support for Unicode text segmentation to JavaScript.

    Bug 1423593
  • Firefox added support for the Screen Wake Lock API.

    Bug 1874849
  • You can now use HTTP(S) and relative URLs when creating WebSockets.

    Bug 1797449
  • Added support for AbortSignal.any.

    Bug 1830781

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