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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.

158.0beta Firefox Beta

September 28, 2026

Version 158.0beta, first offered to Beta channel users on September 28, 2026

Firefox Beta gets updated 3 times a week and as a consequence, the release notes for the Beta 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 via the Firefox Trains website or our @FirefoxBeta Bluesky account.

New

  • You can now fill forms faster in Smart Window. When clicking into a form field or selecting Fill from sources, Smart Window will now suggest data to use based on your relevant open tabs and saved autofill data.

    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.

  • New Tab now keeps a library of custom wallpapers under Your images, rather than only the most recent one.

  • Firefox now supports the new JPEG XL image format which generally has better compression than WebP, JPEG, PNG and GIF and is designed to supersede them.

Fixed

  • Menus such as the List all tabs menu, the Settings menu, and Unified Search menu are now visually consistent on Windows with a High Contrast theme. The user is now able to customize menu background color and text color when creating a custom theme in Windows Settings by setting Background and Text, respectively.

  • PDF generation (for saving as PDF and also printing on Linux and macOS) now uses SkPDF. This allows PDFs to be more accessible, and also fixes a variety of PDF rendering issues.

Developer

  • Developer Information

  • Fixed an issue where the Network Monitor could miss WebSocket messages if they arrived immediately after a connection was established.

Web Platform

  • Added support for the navigate option for the Notification constructor and ServiceWorkerRegistration.showNotification(), which specifies a URL to navigate to when the notification is clicked.

  • The WebAuthn conditional UI will now be shown on input elements with an autocomplete="webauthn" attribute. Previously, the UI would only be shown on input elements with additional autofill field values, e.g. autocomplete="username webauthn".
    (Learn more)

  • Firefox now supports the cache value for PerformanceResourceTiming.deliveryType, allowing websites to identify resources served from the HTTP cache.

  • Firefox now supports typed arithmetic in CSS calc(), allowing units to be multiplied and divided within math functions.

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Other Resources

Developer Information Complete list of changes for this release Press Kit Mozilla and Firefox News Firefox Extended Support Release All Firefox for Desktop Releases Learn more about Firefox