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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.

123.0a1 Firefox Nightly

December 18, 2023

Version 123.0a1, first offered to Nightly channel users on December 18, 2023

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


  • When translating web pages, we are now also translating text in tooltips (i.e. titles) and text displayed in form controls (i.e. placeholder).

    Bug 1819205


  • Address bar settings can now be found in the Firefox Settings' Search section.

    Bug 1852048


  • The Network Monitor now supports saving a response body to disk through the Save Response As context menu item. This replaces the Save Image context menu item, which only supported saving images.

    Bug 1221964

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, support for the Screen Wake Lock API is available in Nightly builds.

    Bug 1589554
  • Starting with Firefox 122, Nightly builds include support for Unicode text segmentation to JavaScript.

    Bug 1423593
  • We now implement linearRGB interpolation for SVG gradients, as well as the existing sRGB interpolation. You can choose which to use via the color-interpolation property.

    Bug 298281
  • Previously, SVG feImage elements that pointed to SVG content required the SVG document to have a root element that had non-percentage width and height values. Such content will now fall back to use the default replaced element values of 300px width and 150px height and the feImage will no longer fail to render.

    Bug 1097856
  • By enabling Preload and Modulepreload support, Early Hints are now fully supported.

    Bug 1874445
  • Audio echo cancellation can now be applied to microphone inputs when the audio output is redirected to another device with setSinkId().

    Bug 1849108
  • Firefox now supports declarative ShadowDOM, providing developers greater flexibility and improved ergonomics when working with ShadowDOMs directly within HTML.

    Bug 1870052


  • Some machines with older AMD CPUs may see image thumbnails incorrectly render as all black in file dialogs. If this is the case, updating the graphics driver should address this issue.

    Bug 1328838

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