New

• By popular request, Full-Page Translations are now available within Firefox extension pages that start with the moz-extension:// URL scheme.

  

• The New Tab custom wallpaper (and colors) option is now available! Your own image can be uploaded as your New Tab wallpaper or any custom color can be selected - from the brightest pink to dark gray. This feature will be rolling out gradually to new users and can also be enabled immediately via Firefox Labs. Additionally, new Wallpaper images and a new Celestial category have also been added.

  

• Link Previews is currently available as an experimental feature which can be enabled via Firefox Labs in the Firefox settings. After enabling, use the Alt+Shift keyboard shortcut when hovering over a link to see the previews in action!

  

• Address autofill has now been enabled for users in Australia and India.

Fixed

• PNG images with transparency now keep their transparency when pasted into Firefox.

• The upload performance of HTTP/3 has been significantly improved, particularly on resumed connections (QUIC 0-RTT) and high-bandwidth and high-delay connections.

• Various security fixes.

Changed

• Due to recent changes in how Chrome encrypts user data on Windows, the Firefox migration wizard can no longer directly import payment methods or passwords from Chrome. However, users can still export passwords from Chrome to a CSV file and then import them into Firefox using the migration wizard or the password manager.

• The Review Checker feature is shutting down and will no longer be available after June 10, 2025.

Enterprise

• You can find information about policy updates and enterprise specific bug fixes in the Firefox for Enterprise 139 Release Notes.

Developer

• Developer Information

• Based on user requests from both Mozilla Connect and Stack Overflow, the filter setting in the Network panel is now preserved across DevTools Toolbox sessions.

• The Debugger's directory root is now scoped to the specific domain where it was set, which aligns with typical usage and avoids applying it across unrelated domains. This builds on previous improvements such as a redesigned UI and easier removal of the root setting. Setting a directory root updates the Source List to show only the selected directory and its children. Learn more

• The appearance of the paused line in the Debugger has been refined for better visibility, especially in high contrast mode.

Web Platform

• The Temporal proposal, a better version of Date, is now enabled by default in Firefox.

• Timer throttling for Workers is now supported.

• Closed <details> elements are now searchable and can be automatically expanded if found via find-in-page.

• Firefox now supports the hidden=until-found attribute, allowing content to be found via find-in-page when it's otherwise hidden by default.

• window.getSelection().toString() now correctly returns the text serialization when text is selected in a text control, improving cross-browser interoperability on some sites.

• Added support for the WebAuthn largeBlob extension.

• Added support for requestClose() to HTMLDialogElement.

• The built-in editor for contenteditable and designMode now handles collapsible white-space(s) before block boundaries and white-space sequences between visible content more consistently with Chrome. As a result, Gecko no longer inserts a padding <br> element after white-space before a block boundary, aligning behavior with other browsers.

Unresolved

• Windows users with certain NVIDIA graphics adapters and multiple monitors running at mixed refresh rates may see graphics corruption after updating to Firefox 139. As a temporary workaround, set the gfx.webrender.dcomp-win.enabled preference to false in about:config and restart Firefox. This issue will be addressed in Firefox 139.0.1.

Community Contributions

• With the release of Firefox 139, we are pleased to welcome the developers who contributed their first code change to Firefox in this release, 14 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:

  • adhaliwal34: 1888339
  • Aidan Harris: 1960339
  • Alexander Kuleshov: 1959970
  • gene smith: 1891962
  • giulianoverrando: 1930777
  • Isaac Briandt: 1944944
  • Jason Jones: 1176600, 1689254, 1855787, 1956009, 1960383
  • Kanaru Sato [:canalun]: 1947061, 1958528, 1961558
  • keanucuco: 1855839
  • lucas.chollet: 1862235
  • Raksha Kumari: 1947278
  • Ricardo Delgado Gomez: 1815793, 1952132, 1960409
  • Sangie[:sangie50]: 1958324
  • Yakub Abdulrahman Alada: 1917908

Fixed

• Fixed a crash that could occur when viewing websites that use WebGL. (Bug 1961191)

• Fixed an issue where the browser could repeatedly crash when certain SVG effects (like blur or drop shadow) were applied to very small areas. (Bug 1924241)

• On Linux, fixed an issue where video playback would appear washed-out on Wayland when HDR support was unavailable. (Bug 1961610)

• Fixed an issue where the "Match Case" shortcut Alt+C in the find-in-page toolbar did not toggle the checkbox as expected. (Bug 1952611)

• Reference link to 138.0.1 release notes.

Fixed

• Fixed an issue which caused a blank page to be shown for Home and New Tab pages for some users. (Bug 1963537)

• Added a workaround for a bug in outlook.office.com/outlook.live.com where attachment filenames are incorrectly prefixed with UTF-8 when saved. (Bug 1961710)

• Reference link to 138.0 release notes.

New

• Profile management helps protect your privacy and stay focused by separating your online life into distinct profiles — for work, school, vacation planning, or whatever you choose. You can now name your profiles and customize them with avatars and color themes for easy recognition, then quickly switch between them — all while keeping bookmarks, tabs, and browsing history completely separate.

  

  

  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.

• Users in the United States can now trigger weather suggestions in the address bar! Simply type a weather-related term or a city name, and view the result directly in the address bar dropdown.

  

  Currently available in: United States
  

  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.

• Tab Groups, a new way to organize and take control of your tabs, is now available to all users worldwide. You can create a group by dragging one tab onto another, pausing, then dropping it. You can also now reposition a tab group on the tab bar by dragging it.

• Firefox on Windows 11 now uses acrylic-style menus for popup windows, which better match the operating system’s aesthetic.

• You can now copy links from background tabs using the tabstrip context menu on MacOS and Linux.

Fixed

• Various security fixes.

Changed

• Improved the address and credit card autofill experience to better handle forms that update dynamically as users input information. Autofill now correctly fills newly revealed fields—such as those shown after selecting a country.

• Rededicated previous color settings to Contrast Control settings. (Learn more)

Enterprise

• You can find information about policy updates and enterprise specific bug fixes in the Firefox for Enterprise 138 Release Notes.

Developer

• Developer Information

• Added support for the import map integrity field, allowing you to ensure the integrity of dynamically or statically imported modules.

• Implemented support for Error.isError, enabling brand checks to determine whether an object is an instance of Error. (Learn more)

• Added support for the error.captureStackTrace extension to improve compatibility with other browsers. (Learn more)

• A new column has been added to the Network panel to display the full path of the request URL. This enhancement makes helps developers quickly view and analyze complete request paths.

• Firefox now applies a uniform user agent (UA) style to <h1> elements, regardless of whether they are used inside <article>, <aside>, <nav>, or <section>. (Learn more)

  

  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.

Web Platform

• Added support for Import Attributes, allowing developers to specify additional metadata when importing modules.

• Applications can now set their preferred degradation method to be used when the configured frame rate and resolution cannot be maintained. (Learn more)

• Firefox now enables the cache directive for the Clear-Site-Data header, allowing websites to clear the network cache. This gives websites more control over stored data, such as clearing the cache during logout to help mitigate privacy risks. (Learn more)

Unresolved

• Due to recent changes in Chrome on Windows, some users might find that the Firefox migration wizard no longer successfully imports passwords from Chrome or Chrome-based browsers. As a workaround, you can export your passwords as a CSV file from Chrome and then import them into Firefox using either the migration wizard or the Firefox password manager.

Community Contributions

• With the release of Firefox 138, we are pleased to welcome the developers who contributed their first code change to Firefox in this release, 18 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:

  • Abdelaziz Mokhnache: 1932626, 1950987
  • Brian Ouyang: 1950467
  • Chris Shiohama: 1953971
  • cob.bzmoz: 1947667, 1956149, 1956163
  • Cruz Hernandez: 1947000
  • erosman [:erosman]: 1869171, 1951166
  • Gautam Panakkal: 1775913, 1917910
  • Harold Camacho: 1935513, 1936819
  • Ihar Hrachyshka: 1939555
  • Jacob Wood: 1915523
  • Janik Haag: 1953297
  • Jishnu Murali Thampan: 1828113, 1947594
  • joel.mozillaosi: 1950008
  • Joshua O'Brien: 1948347, 1952022
  • Luke Taylor [:ltaylor]: 1953199, 1953206
  • Ngo Fong: 1953748
  • Sandi Vujaković [:elsandosgrande]: 1951697
  • Shane Ziegler: 1953980, 1954799, 1955586