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Firefox 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.

86.0 Firefox Release

February 23, 2021

Version 86.0, first offered to Release channel users on February 23, 2021

We'd like to extend a special thank you to all of the new Mozillians who contributed to this release of Firefox.

At Mozilla, we believe you have a right to privacy. You shouldn’t be tracked online. Whether you are checking your bank balance, looking for the best doctor, or shopping for shoes, unscrupulous tracking companies should not be able to track you as you browse the Web. For that reason, we are continuously working to harden Firefox against online tracking of our users.



  • Reader mode now works with local HTML pages.

  • Using screen reader quick navigation to move to editable text controls no longer incorrectly reaches non-editable cells in some grids such as on

  • The Orca screen reader's mouse review feature now works correctly after switching tabs in Firefox.

  • Screen readers no longer report column headers incorrectly in tables containing cells spanning multiple columns.

  • Links in Reader View now have more color contrast.

  • Various security fixes.


  • On Linux and Android, the protection to mitigate the stack clash attack has been activated.

  • From Firefox 86 onward, DTLS 1.0 is no longer supported for establishing WebRTC's PeerConnections. All WebRTC services need to support DTLS 1.2 from now on as the minimum version.

  • Consolidated all video decoding in the new RDD process which results in a more secure Firefox.



  • Inactive CSS tool is now showing a warning when margin or padding is set on internal table elements.
    Inactive CSS screenshot

  • Developer Tools Toolbox is now showing a number of errors on the current page. This is a quick way to surface information to a developer that something is wrong with their page. Clicking on the red exclamation icon navigates the user to the Console panel.
    Develeoper tools: screenshot of number of errors

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