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Firefox 34 Find out what is new

Mozilla is rolling out updates for specific versions of the web browser. If you are running a non-stable build you may have already received updates last week as Mozilla postponed the release of the stable version and the ESR version by one week to get additional development time to stabilize development.

This means that stable users will receive the upgrade to version 34, Beta users to 35, Developer Edition (former Aurora) users to version 36, and Nightly users to 37.

In fact, some version have already been upgraded by Mozilla in the past but the stable update is definitely coming this week.

To find out which version and channel you are running type about:support in the browser's address bar and hit enter. You find the information listed under Application Basics there.

Firefox 34 Download

firefox 34 stable

Mozilla will make available the update to Firefox 34 in a bit. As always, it is already available on the official (and public) ftp server from where it can be downloaded.

Several third-party downloads sites are also hosting the Firefox 34 download already.

It is possible that Mozilla will push another version out to users if last minute changes demand it. It is best usually to wait for the official release announcement before the new version is downloaded.

Most users of the browser will receive the update via the built-in automatic update functionality but it will be made available on the official Mozilla website as well.

Firefox 34 Changes

Firefox 34 introduces several changes and improvements to the browser. The following paragraphs list the most important of them.

New Search Bar Behavior

firefox search beta

I have reviewed this when it landed in Firefox Beta. It changes Firefox's separate search form that is displayed by default in several ways.

Most notable is the display of other search providers installed in the browser so that you can run searches using them instead of the default search engine with just a click.

Mozilla added a search tab to Firefox's options which you can use to manage the search providers more comfortably in the browser.

firefox search preferences

You can change the default search engine there and select which search engines you want displayed as one-click options in the search form.

Firefox users who don't like the change can disable it in the following way:

  1. Type about:config in the browser's address bar and hit enter.
  2. Confirm you will be careful if the prompt appears.
  3. Search for and set it to false.

Note: This is currently only available in the US version of Firefox.

Firefox Hello


This is a new real-time communication feature of Firefox using WebRTC. It enables you to communicate with friends, family and colleagues using the browser and nothing else.

What you may find interesting about it is that it does not require the creation of an account to communicate with other users. You have to exchange a link then. Users who don't mind the creation of accounts can use their Firefox account to save contacts and other information so that they are always available right away in the browser without having to exchange links first.

Firefox Hello supports voice and video calls and requires no additional software or plugins.

Mozilla is rolling out the feature gradually. To get it right away, set the preference loop.throttled to false and restart Firefox. Hello should be available then,

Check out my full review of Firefox Hello here.

Theme switching in customize menu

firefox customize themes

If you switch themes regularly you may like the option to do so in the new customize menu.  You find five default "light" themes that Firefox ships with there that you can switch between.

You find installed Personas themes there as well so that you can switch between them. Please note that this does not include so-called complete themes in any way as they are not listed there at all.

It is still possible to enable, disable or uninstall themes in the add-ons manager.

Firefox is already running on Windows fix

firefox already running

Firefox is already running can come up when you try to open Firefox when a browser process is still running on the system. This can happen when the Firefox profile is locked for example and can be caused by Firefox running exit processes in the background before the process itself is terminated (say you have configured it to delete temporary data on exit for example).

From Firefox 34 on, Windows users receive a different message that they can use to close that Firefox process which terminates it on the system.

It is like you opening the Task Manager and killing the Firefox process manually, only faster.

I have reviewed the new feature here in detail.

Other Changes

  • Default search engine changed to Yandex for Belarusian, Kazakh, and Russian locales.
  • Disabled SSLv3.
  • Firefox signed by Apple OS X version 2 signature
  • HTTP/2 (draft14) and ALPN (Application-Layer Protocol Negotiation) implementation.
  • Proprietary window.crypto properties/functions re-enabled (to be removed in Firefox 35)
  • Wikipedia search is using https now (US-only).

Developer Changes


  • New Storage Inspector. This needs to be enabled in the Firefox Developer Tools (press F12) first before you can use it. Locate Storage in the options and check the box next to it to enable it. Additional information here.
  • WebIDE enabled by default. Shipped in Firefox 33 but was disabled by default. You can use it to run and debug Firefox OS apps. Additional information here.
  • Performance tool revamped Profiler interface and frame rate timeline.
  • jquery events visible in Page Inspector
  • console.table support
  • CSS Fonts Level 3 progress.
  • WebCrypto: RSA-OAEP, PBKDF2, AES-KW and ECDH support.
  • ECMAScript 6 Weak6.
  • JavaScript Template Strings.

Firefox 34 for Android

Firefox for Android and the desktop version of Firefox share improvements. This part of the review looks only at Android-specific changes.

Chromecast Mirror Tab support

firefox android mirrorcast

Firefox for Android users who also own a Chromecast can mirror tabs displayed in the mobile browser now. This is done by tapping on the menu button on the device and selecting Tools > Mirror Tab from the context menu that opens up.

All devices are displayed on the next screen and all that is left to do is pick one of them to start the mirroring process. To stop the process tap on the menu button again and select stop mirror from there.

  • Added support for Prefer:Safe HTTP Header - If parental controls are enabled, Firefox will send a Prefer:Safe header to every site and service that is visited using it. Sites that support the header may deliver different contents or restrict access to some contents.
  • Device Storage API for privileges apps enabled. Additional information here.
  • Public Key Pinning support enabled - This allows sites to specify certificate authorities on first connect. Firefox will then use these information on future connections to those sites.
  • Theme refresh
  • Redesigned first run experience
  • Fixed: mp4 videos on Android L
  • Unresolved: Flash and mp3 does not work on Android L.

Security updates / fixes

Security updates are published after the release of Firefox. We will add those once they become available.

  • MSFA-2014-89 Bad casting from the BasicThebesLayer to BasicContainerLayer
  • MSFA-2014-88 Buffer overflow while parsing media content
  • MSFA-2014-87 Use-after-free during HTML5 parsing
  • MSFA-2014-86 CSP leaks redirect data via violation reports
  • MSFA-2014-85 XMLHttpRequest crashes with some input streams
  • MSFA-2014-84 XBL bindings accessible via improper CSS declarations
  • MSFA-2014-83 Miscellaneous memory safety hazards (rv:34.0 / rv:31.3)

Additional information / sources


This article was first seen on ComTek's "TekBits" Technology News


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