Firefox 142.0

For users in the United States, article recommendations on your New Tab page are now grouped into topic sections like Sports, Food, and Entertainment to make stories more organized and easier to scan. You can also follow topics you’re interested in and block ones you’d prefer not to see, giving you more control over what shows up when you open a new tab. This feature is part of a progressive roll out. What is a progressive roll out? Certain new Firefox features are released gradually. This means some users will see the feature before everyone does. This approach helps to get early feedback to catch bugs and improve behavior quickly, meaning more Firefox users overall have a better experience.

You can now see what’s behind a link before visiting it with Link Previews. Long press a link (or right-click and choose Preview Link ). Previews can optionally include AI-generated key points, which are processed on your device to protect your privacy. Link Previews is gradually rolling out to ensure performance and quality and is now available in en-US , en-CA , en-GB , en-AU for users with more than 3 GB of available RAM. This feature is part of a progressive roll out. What is a progressive roll out? Certain new Firefox features are released gradually. This means some users will see the feature before everyone does. This approach helps to get early feedback to catch bugs and improve behavior quickly, meaning more Firefox users overall have a better experience.

On Windows, clicking a persistent notification when Firefox is closed or restarted will now properly open Firefox with the relevant webpage, instead of just opening the main page of the website.

ETP Strict mode now supports a flexible exception list to fix broken site features caused by tracker blocking. Exceptions are split into baseline (core functionality) and convenience (extra features), letting users choose improved site compatibility without compromising key privacy protections.

Keep an active tab visible in a collapsed tab group Focus on just one tab in a group without the clutter. Your active tab stays in view, keeping things tidy even with the group collapsed.

You can now remove extensions from the sidebar by right-clicking the extension icon and selecting Remove from Sidebar .

Improved the scroll speed in the bookmarks dialog to not go beyond the component area.

Improved drag-and-drop support for blob images.

Improved search results from browsing history via the address bar, reducing the likelihood of duplicate results being shown.

Improved Netmonitor so that Request Headers/Cookies/Params are displayed in the Network panel even if the request isn't finished yet.

Multiselecting non-contiguous tabs to drag may result in toolbar unresponsiveness or visual glitches. Dragging any single tab should resolve this. We will be landing a fix in the next dot release with Bug 1984342 .

Various security fixes .

You can find information about policy updates and enterprise-specific bug fixes in the Firefox for Enterprise 142 Release Notes .

Developer Information

Firefox now supports the wllama API for extensions, enabling developers to integrate local language model (LLM) capabilities directly into their add-ons.

The Debugger now offers a new setting to control whether the debugger overlay is shown during paused script execution.

Firefox now supports the Prioritized Task Scheduling API , enabling developers to assign and manage task priorities.

The Selection.getComposedRanges() API is now available, allowing developers to accurately get selected text ranges across shadow DOM boundaries.

Added support for the URLPattern API , enabling developers to match and parse URLs using a standardized pattern syntax.

With the release of Firefox 142, we are pleased to welcome the developers who contributed their first code change to Firefox in this release, 20 of whom were brand new volunteers! Please join us in thanking each of these diligent and enthusiastic individuals, and take a look at their contributions: Alex Stout: 1845523

Cookies created with cookies.set() in Nightly are now validated, and invalid cookies are rejected. The implementation in Nightly is to enable monitoring for any issues. The intention is to enforce validation in all channels in a future release. ( Firefox bug 1976197 )

The cookies methods now accept and return milliseconds in the fractional part of expirationDate . ( Firefox bug 1972757 )

Adds the browserAction.onUserSettingsChanged and action.onUserSettingsChanged events that listen for changes in the user-specified settings that affect an extension's action. ( Firefox bug 1828220 )

Adds browserSettings.verticalTabs , which enables extensions to control whether the browser displays the tab bar horizontally or vertically. ( Firefox bug 1946600 )

Enabled the Firefox built-in data collection consent feature for Firefox for Android. See the Extension Workshop article Firefox built-in consent for data collection and transmission . ( Firefox bug 1954524 )

anchor-size() (Nightly): layout.css.anchor-positioning.enabled The CSS anchor-size() function enables setting anchor-positioned element's size, position, and margins relative to the dimensions of anchor elements. ( Firefox bug 1972610 ).

:heading and :heading() : layout.css.heading-selector.enabled The CSS :heading pseudo-class allows you to style all heading elements ( <h1> - <h6> ) at once rather than targeting them individually. The :heading() functional pseudo-class allows you to style heading elements that match the given heading levels. ( Firefox bug 1974386 ).

view-transition-name: match-element (Nightly): dom.viewTransitions.enabled The match-element value of the CSS view-transition-name property automatically assigns a unique internal view-transition-name to each selected element, rather than having to name them individually. ( Firefox bug 1956141 ).

Integrity-Policy and Integrity-Policy-Report-Only for scripts (Nightly): security.integrity_policy.enabled The Integrity-Policy and Integrity-Policy-Report-Only HTTP headers are now supported for script resources. These allow websites to either enforce subresource integrity guarantees for scripts or only report violations of the policy, respectively. ( Firefox bug 1976656 ).

Integrity-Policy and Integrity-Policy-Report-Only for stylesheets: security.integrity_policy.stylesheet.enabled The Integrity-Policy and Integrity-Policy-Report-Only HTTP headers are now supported for stylesheet resources. These allow websites to either enforce or only report violations of the policy, respectively. ( Firefox bug 1974247 ).

The <object> element no longer supports the deprecated codebase attribute. Use the data attribute instead. (See Firefox bug 1973900 for more details.)

The & selector inside @scope no longer inherits the specificity of the scope start selector . This makes & selectors in @scope consistent with CSS nesting , avoiding unexpected specificity differences (see CSS nesting and specificity ). ( Firefox bug 1975531 ).

The URL Pattern API is fully supported, enabling you to match and parse URLs using a standardized pattern syntax. ( Firefox bug 1731418 ).

The File and Directory Entries API now fully supports the HTMLInputElement.webkitdirectory (and corresponding HTML webkitdirectory attribute) and File.webkitRelativePath properties on Firefox Android. This lets you configure an <input type="file"> element to accept directories instead of files ( Firefox bug 1973726 ).

The Selection.getComposedRanges() method is now supported, allowing developers to accurately get selected text ranges across shadow DOM boundaries. In addition, the methods setBaseAndExtent() , collapse() , and extend() of the Selection interface have been modified to accept nodes inside a shadow root. ( Firefox bug 1903870 ).

The Animation.overallProgress property is now supported, allowing developers to track and display progress through an animation. ( Firefox bug 1834878 ).

The Animation.commitStyles() method no longer requires fill to be set on an animation to commit the computed styles after the animation has finished. Note that until more browsers support this change, you should continue to set fill . ( Firefox bug 1973203 ).

The Prioritized Task Scheduling API is now supported, providing a standardized mechanism to assign and manage task priorities for an application. The supported interfaces include: Scheduler , TaskController , TaskSignal , TaskPriorityChangeEvent (and the prioritychange event), and the properties Window.scheduler and WorkerGlobalScope.scheduler . The Scheduling interface and the Navigator.scheduling property are not supported. ( Firefox bug 1966997 ).

The currentRoundTripTime , totalRoundTripTime , and responsesReceived properties of the RTCIceCandidatePairStats dictionary are now supported. These return the current round trip time (RTT) and the information needed to calculate the average RTT for the connection. ( Firefox bug 1371391 ).

The setParameters() and getParameters() methods of the RTCRtpSender interface now support setting and getting the specific codec used for each encoding . You can also set a codec for each encoding in the init.sendEncodings array that's passed to the addTransceiver() method of the RTCPeerConnection interface. ( Firefox bug 1894137 ).

The estimatedPlayoutTimestamp , framesAssembledFromMultiplePackets , freezeCount , jitterBufferMinimumDelay , jitterBufferTargetDelay , keyFramesDecoded , pauseCount , totalAssemblyTime , totalFreezesDuration and totalPausesDuration properties of the RTCInboundRtpStreamStats interface are now supported. ( Firefox bug 1926622 ).

Removed FTP proxy support from WebDriver capabilities ( Firefox bug 1972670 ).

Updated the expiry value of all the cookies set via WebDriver BiDi and WebDriver classic (Marionette) to be limited to 400 days ( Firefox bug 1974394 ).

Implemented the new emulation.setLocaleOverride command which allows clients to override a locale in JavaScript APIs ( Firefox bug 1968952 ).

Improved setting a proxy with browsingContext.createUserContext : added support for host patterns like .mozilla.org in noProxy property ( Firefox bug 1977180 ) and fixed a bug where setting an HTTP proxy did not allow navigation to HTTPS URLs ( Firefox bug 1977168 ).

Fixed a bug where browsingContext.create would fail after a browsingContext.print command was interrupted by closing a tab with the browsingContext.close command ( Firefox bug 1841125 ).

Updated the session.end command to resume all requests which were blocked by network interceptions ( Firefox bug 1974426 ).

Updated the WebDriver:AddCookie command to throw an error when a target cookie has sameSite=none and secure=false attributes ( Firefox bug 1977205 ).

Removed the dialog text value from the unexpected alert open error message, since the dialog text is available now via the data field ( Firefox bug 1948236 ).