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A community-driven Web developer engagement initiative focused on the backward compatibility and regressions in Firefox. Documents, latest updates & more.

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Firefox 71 Beta and Developer Edition are now available for testing, and our site compatibility notes are also ready to be browsed.

The new release comes with various deprecations including Application Cache, TLS 1.0/1.1, -moz-touch-enabled media feature and legacy MathML features. Some sites are known to have a rendering issue as the X-Content-Type-Options HTTP header is now applied to top-level documents.

Read through all the Firefox 71 compatibility notes to get prepared for the final release in December. Plus, don’t forget to install our Firefox DevTools extension to not miss upcoming changes!

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