Firefox Nightly
Release Notes

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.

Firefox now prompts 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.

Firefox has expanded its download protection and now more proactively blocks downloads from URLs that are considered to be potentially untrustworthy.

The URL Paste Suggestion feature provides a convenient way for users to quickly visit URLs copied to the clipboard in the address bar of Firefox. When the clipboard contains a URL and the URL bar is focused, an autocomplete result appears automatically. Activating the clipboard suggestion will navigate the user to the URL with 1 click.

Firefox now provides an option to enable Web Proxy Auto-Discovery (WPAD) while configured to use system proxy settings.

Users of tab-specific Container add-ons can now search in the Address Bar for tabs that are open in different containers. Special thanks to volunteer contributor atararx for kicking off the work on this feature!

It is now possible to highlight in PDFs.

Starting with Firefox 125, Nightly builds support resolving HTTPS DNS records with the operating system's DNS resolver on specific platforms (Windows 11, Linux, Android 10+) without requiring DNS over HTTPS to be enabled. This capability allows the use of HTTP/3 without needing to use the Alt-Svc header, upgrades requests to HTTPS when the DNS record is present, and enables wider use of ECH. This feature is expected to ship in Firefox 126.

In a group of radio buttons where no option is selected, the tab key now only reaches the first option, rather than every option being reachable with tab. The arrow keys navigate between options as they do when there is a selected option. This makes keyboard navigation more efficient and consistent.

Firefox for Android no longer includes the variant and extension of BCP47 in the Accept-Language header of HTTP requests for better interoperability with other browsers.

Added support for the content-box and stroke-box keywords of the transform-box CSS property.

Support for SVGAElement.text was removed in favor of the more widely-implemented SVGAElement.textContent method.

Starting with Firefox 125, the transition-behavior CSS property is now supported 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.

align-content works now in block layout, allowing block direction alignment without needing a flex or grid container.

Enabled WebAssembly multi-memory by default. Wasm multi-memory allows wasm modules to use and import multiple independent linear memories. This enables more efficient interop between modules, and better polyfills for upcoming wasm standards like the component model.

Starting with Firefox 125, Nightly builds will attempt to establish TLS connections using a hybrid post-quantum key agreement mechanism (X25519+Kyber768). This may result in slow TLS handshakes or failed connections on networks with TLS intercepting middleboxes. The feature can be disabled by setting the security.tls.enable_kyber preference to false.

Starting with Firefox 124, Nightly builds include support for the Screen Wake Lock API.

Added support for Unicode text segmentation to JavaScript.

Some macOS Nightly users may see a prompt like the one below when trying to update a more recent build:

While the underlying cause of this bug was identified and resolved, users in this state should follow the instructions from the prompt and manually reinstall. No data will be lost in the process and this should only need to be done once for automatic updates to resume.