Firefox 83 for developers

This article provides information about the changes in Firefox 83 that will affect developers. Firefox 83 was released on November 17, 2020.

Note: See also Firefox 83 is upon us on Mozilla hacks

Changes for web developers

Developer Tools


  • The crossorigin attribute is now supported for <link rel=icon> (bug 1661075).
  • The displaystyle attribute is now implemented for all MathML elements (bug 1666075).




No changes.


No changes.

WebDriver conformance (Marionette)

  • We've removed preliminary support for WebDriver:SwitchToShadowRoot, which hasn't been added to the WebDriver specification yet (bug 1662468).
  • We fixed a bug in WebDriver:Back and WebDriver:Forward that caused Marionette to hang when the navigation was triggered from within an <iframe> that gets removed (bug 1672758).

Changes for add-on developers

No changes.

Older versions