Site Compatibility for Firefox 32


Firefox 32 was released on . While it has been developed to maintain compatibility as much as possible, the new version includes some changes affecting backward compatibility aimed at improving interoperability with the other browsers or following the latest Web standards. Here's the list of such changes — hope this helps whenever you test your sites or applications.

This article only explains the changes that may affect backward compatibility for websites. For the other new features and changes, please read the following documents:

Follow @FxSiteCompat on Twitter for further updates.

Previously, the navigator.doNotTrack property was incorrectly returning "yes" even when the Do Not Track option was being disabled by the user. Starting with Firefox 32, it returns "0" (disabled), "1" (enabled) or "unspecified" to follow the spec.

new Document() now returns Document instead of XMLDocument

The Document constructor starts returning a Document object instead of XMLDocument to follow the latest spec. They are identical except the load method which is only available on XMLDocument. The DOMImplementation.createDocument method continues returning an XMLDocument object.

HTMLCollection no longer matches an empty string name

Previously, the empty named property of an HTMLCollection object, like document.forms[0][""], was returning the first unnamed child element. This behavior has been changed to return undefined to match the updated spec.

HTMLTableElement.insertRow now always inserts the row to <tbody>

The behavior of the HTMLTableElement.insertRow method has been changed to follow the latest HTML5 spec. When there is a <thead> but no <tbody> and <tr>, the new <tr> will be inserted to a newly created <tbody> instead of the existing <thead>.

WindowUtils has been removed

As part of the ongoing effort to standardize global objects, the non-standard WindowUtils interface has been removed from window.

window.openDialog has been removed

The non-standard window.openDialog method is no longer available from Web content. should be used instead.


Cache backend has been overhauled

The new HTTP cache backend has been landed on Firefox 32 to improve the page load performance. See Honza Bambas' blog post for details. If you encountered any regressions, please report the issue to Bugzilla.


Several 1024-bit root certificates have been removed

As part of the ongoing security improvements, several SSL and code signing trust bits for 1024-bit root certificates have been removed from Network Security Services (NSS) used in Firefox and other products. Those include AC Raíz Certicámara,, GTE CyberTrust, NetLock, TDC Internet, ValiCert and VeriSign. 1024-bit root certificates will all be removed over the next few Firefox releases, because these are no longer considered as secure.


onconnection and onclosedconnection have been dropped

The onconnection and onclosedconnection properties have been removed from the RTCPeerConnection interface, currently implemented as mozRTCPeerConnection, since they are no longer in the spec.