Fixed

• Fixed a bug where "Cookies and site data" and "Temporary cached files and pages" were unexpectedly enabled after updating to Firefox 136 for users with "History" and/or "Site settings" set to clear on shutdown in previous versions. (Bug 1952564)

  Affected users already on Firefox 136 can disable these settings in "Privacy & Security".

• Fixed an issue where the Primary Password prompt appeared in unexpected situations. (Bug 1946121)

• Fixed visibility issues with radio buttons on dark backgrounds. (Bug 1951930)

• Fixed high CPU usage on Windows when the screen was locked or the laptop lid was closed. (Bug 1924932)

Web Platform

• Disabled support for the CookieStore API due to compatibility concerns. The API will be enabled later once the compatibility issues have been addressed.

• Reference link to 136.0.1 release notes.

Fixed

• Fixed an issue where a cookie size limit caused problems with website cookie management when using the CookieStore API. This could cause login and other state-related issues. (Bug 1950565)

• Fixed an issue where Control/Command+L did not focus the address bar in new windows. (Bug 1947723)

• Reference link to 136.0 release notes.

Unresolved

• Users clearing "History" and/or "Site settings" on shutdown on previous versions will also have clearing "Cookies and site data" and "Temporary cached files and pages" enabled after updating to Fx136 even if they previously haven't checked these settings.
  Affected users can go to "Privacy & Security" settings directly after the upgrade and uncheck both boxes to avoid getting logged out. (Bug 1952564)

New

• You can now enable the updated Firefox sidebar in Settings > General > Browser Layout to quickly access multiple tools in one click, without leaving your main view. Sidebar tools include an AI chatbot of your choice, bookmarks, history, and tabs from devices you sync with your Mozilla account.

  

• Keep a lot of tabs open? Try our new vertical tabs layout to quickly scan your list of tabs. With vertical tabs, your open and pinned tabs appear in the sidebar instead of along the top of the browser. To turn on vertical tabs, right-click on the toolbar near the top of the browser and select Turn on Vertical Tabs. If you’ve enabled the updated sidebar, you can also go to Customize sidebar and check Vertical tabs. Early testers report feeling more organized after using vertical tabs for a few days.

  

• The Clear browsing data and cookies dialog now allows clearing saved form info separately from browsing history.

  

• Smartblock Embeds allows users to selectively unblock certain social media embeds that are blocked in ETP Strict and Private Browsing modes. Currently, support is limited to a few embed types, with more to be added in future updates.

• Firefox now upgrades page loads to HTTPS by default and gracefully falls back to HTTP if the secure connection fails. This behavior is known as HTTPS-First.

• On macOS, some background tabs will be moved to lower power cores, reducing energy usage.

• Hardware-accelerated playback of HEVC video content is now supported on macOS.

• Hardware video decoding is now enabled for AMD GPUs on Linux.

• On Linux, Firefox is now available on ARM64 (AArch64), with installation options via APT and tarballs. Flatpak support is coming soon.

• The Weather forecast on the New Tab page is expanding to additional regions, including Mexico, Brazil, Argentina, and Chile, as part of an ongoing regional rollout.

  

  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.

• Address autofill enabled for users in the United Kingdom.

  

  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.

Fixed

• Firefox will now prefer the PNG format when copying images out of Firefox, allowing the preservation of transparency.

• Various security fixes.

Changed

• For New Tab stories, the Save to Pocket action was moved from a button to the context menu along with other actions, such as Bookmark.

• The macOS DMG installer packages now use LZMA for compression, reducing download size and installation time.

• Due to recent changes in macOS Sequoia, the shortcut for completing search strings to .com addresses has been changed from Ctrl+Enter to Cmd+Enter.

Enterprise

• You can find information about policy updates and enterprise specific bug fixes in the Firefox for Enterprise 136 Release Notes.

Developer

• Developer Information

• The Developer Tools debugger editor now uses Codemirror 6, which improves performance.

Web Platform

• Added support for the Intl.DurationFormat object; this enables language-sensitive duration formatting.

• Added support for the CSS :open pseudo-class for styling elements that can be toggled “open” to display more content.

• Added support for the :has-slotted pseudo-class, allowing authors to style the contents of a <slot> element when it is not empty or not using the default value.

• Added support for the CookieStore API, an asynchronous cookie API for scripts running in HTML documents and service workers.

• Added support for ARIA elements reflection.

• Firefox now sends a referrer from meta refreshes and Refresh headers.

• Added support for sending and receiving the AV1 video codec over WebRTC. Both singlecast and simulcast are supported for sending.

• Added support for sending multiple simultaneous versions of the same source over WebRTC, commonly called simulcast, with the H264 video codec. H264 is the second video codec after VP8 to be supported for sending simulcast.

• The value plaintext-only can now be specified for the contenteditable attribute, making the raw text of an element editable but without supporting rich text formatting.

• Added support for the text replacement feature in an input field on macOS. Web content can enable/disable this using the HTML autocorrect attribute.

Unresolved

• Users clearing "History" and/or "Site settings" on shutdown on previous versions will also have clearing "Cookies and site data" and "Temporary cached files and pages" enabled after updating to Fx136 even if they previously haven't checked these settings.
  Affected users can go to "Privacy & Security" settings directly after the upgrade and uncheck both boxes to avoid getting logged out. (Bug 1952564)

Community Contributions

• With the release of Firefox 136, we are pleased to welcome the developers who contributed their first code change to Firefox in this release, 10 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:

  • Arkadiy Tetelman: 1939981
  • asthetik: 1868306
  • carlos: 1930334
  • Jonas Haukenes [:johauke]: 1932184
  • Karan Yadav: 1007374, 1513984, 1873929, 1940223
  • Krzysztof Jan Modras [:chrmod]: 1941821
  • Meike [:mei]: 1940009
  • Mitchell Ament: 1942327
  • Nathan Teodosio :nteodosio: 1924319
  • Roland Kossel: 1927764

New

• Firefox Translations now supports more languages than ever! Pages in Simplified Chinese, Japanese, and Korean can now be translated and Russian is now available as a target language for translating into.

• The credit card autofill feature is now being gradually rolled out to all users globally.

  

  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.

• AI Chatbot access is now being gradually rolled out to all users. To use this optional feature, choose AI Chatbot from the sidebar or from Firefox Labs. Then, complete the provider selection to see the chat interface become available on the sidebar.

  

  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.

• Firefox now enforces certificate transparency, requiring web servers to provide sufficient proof that their certificates were publicly disclosed before they will be trusted. This only affects servers using certificates issued by a certificate authority in Mozilla's Root CA Program.

• Additionally, the CRLite certificate revocation checking mechanism is also being gradually rolled out, substantially improving the performance of these checks.

  

  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.

• Firefox now includes safeguards to prevent sites from abusing the history API by generating excessive history entries, which can make navigating with the back and forward buttons difficult by cluttering the history. This intervention ensures that such entries, unless interacted with by the user, are skipped when using the back and forward buttons.

• 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.

Fixed

• Made improvements to the Translations feature which will reduce the likelihood that models will invent new, made-up words under some circumstances.

• Various security fixes.

Changed

• The refreshed New Tab layout previously rolled out in Firefox 134 to users in the United States is now being made available in all countries where Stories are available. It features a repositioned logo to prioritize Web Search, Shortcuts, and Recommended Stories at the top. The update also includes changes to the card UI for recommended stories and allows users with larger screens to see up to four columns for better use of space.
  

  

  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.

• The “Do Not Track” checkbox has been removed from preferences. If you wish to ask websites to respect your privacy, you can use the “Tell websites not to sell or share my data” setting instead. This option is built on top of the Global Privacy Control (GPC).

• 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. This option can also now be used on plain text links.

• Linux binaries are now provided in XZ format, replacing the previous BZ2 format, offering faster unpacking and smaller file sizes.

Developer

• Developer Information

• A warning is now displayed when content-visibility is used on elements where size containment does not apply.

• Introduced a new console command $$$ that allows searching the page, including within shadow roots.

• Enhancements to WebExtension debugging: Workers are now available in the Console panel’s context selector and breakpoints function correctly in content scripts.

Web Platform

• Added support for a post-quantum key exchange mechanism (mlkem768x25519) for HTTP/3.

• The attribute values which indicate the coordinates of PointerEvent may now be fractional values rather than only integers. This allows web apps to handle the events with higher-precision coordinates when the target element is transitioned by CSS and/or the viewport is zoomed.

• The behavior of mouseenter, mouseleave, pointerenter and pointerleave events was changed for improved spec compliance when the last mouseover or pointerover event target is removed.

• Added support for the WebAuthn getClientCapabilities() method.

Community Contributions

• With the release of Firefox 135, we are pleased to welcome the developers who contributed their first code change to Firefox in this release, 16 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:

  • abdoatef.ab: 1775215
  • Arnaud Vergnet: 1930106
  • ChengYangyang: 1935611, 1937502
  • Dylan O'Toole: 1909931
  • Filipe Laíns: 1935621
  • Floria Fang: 1930885
  • Fredrik: 1922403
  • johndiamond: 1924542
  • Matt Mower: 1921634
  • Mauro B: 1921951
  • Muhammed: 1933441
  • Patrick Shannon: 1930848
  • Rubicon [:rubicon]: 1755647
  • Ruhan: 1894240
  • Toby Cathcart Burn: 1897783
  • Victor Vianna: 1935021

Fixed

• Fixed drop-down menus being unusable on some sites relying on certain mousemove event behavior. (Bug 1944191)

• Fixed scrolling to the wrong location with anchor tags in some situations. (Bug 1946899)

• Fixed being unable to restore closed windows and tabs via the History menu when upgrading from an older Firefox version. (Bug 1947503)

• Fixed broken search functionality when updating to Firefox 135 with a custom search engine with an overly-large icon installed. (Bug 1946156)

• Security fix.

• Reference link to 135.0 release notes.