Firefox 64-bit to support Microsoft Silverlight after all

Martin Brinkmann
Nov 25, 2015
Updated • Nov 26, 2015

Mozilla launches a stable version of Firefox 64-bit for the Microsoft Windows operating system this month in silent fashion. While it is available for download, it is not yet listed on the organization's official download site.

Firefox users can download the 64-bit version from Mozilla's Download Archive though. Since it is the first official stable release, it is likely that Mozilla wanted to monitor bugs and other issues for a release cycle.

One core difference between the 32-bit and 64-bit version of Firefox for Windows lies in plugin support.

Firefox 32-bit users can install plugins like Java, Silverlight or Adobe Flash and they will get picked up by Firefox automatically.

64-bit versions of Firefox on the other hand accept only Adobe Flash and no other plugins even if 64-bit versions of plugins are available.

This is going to change soon however as Mozilla plans to add Microsoft Silverlight to the browser's whitelist.

The reason given is that streaming services such as Amazon or Netflix, as well as several local streaming providers such as Eurosport, Videoload, Sky Go or Magine TV use Silverlight exclusively or optionally.

Mozilla plans to integrate support for Silverlight in 64-bit versions of Firefox in Firefox 43 or 44. It is not clear right now if the organization manages to add support of Silverlight in Firefox 43, to be released on December 15, 2015, or Firefox 44, which will be released on January 26, 2016.

No 64-bit version of Firefox for Windows picks up the plugin currently.

Support for Microsoft Silverlight will be temporary only, as Mozilla announced some time ago that it will retire NPAPI support in Firefox at the end of 2016.

This ends support for Silverlight and other browser plugins that depend on NPAPI in all versions of the Firefox web browser.

It is interesting to note that Firefox is one of the few mainstream browsers left that supports Silverlight. Neither Google with its Chrome browser nor Microsoft's new browser Edge support Silverlight anymore.

This leaves users with two options. First, they can block updates of the browser to retain plugin functionality, or keep an older copy around for that purpose, or they may use a browser that won't discontinue support. Pale Moon for instance won't follow Mozilla, Google and Microsoft according to a post on the official forum.

Closing Words

I think that browser developers should leave it up to the user to install and use plugins, provided that they don't cause instabilities or have known security vulnerabilities.

That does not mean that they cannot protect their users by default, for instance by setting plugin contents to "click to play" instead of running them right away. (via Sören Hentzschel)

Now You: Do you use Silverlight?

Firefox 64-bit to support Microsoft Silverlight after all
Article Name
Firefox 64-bit to support Microsoft Silverlight after all
Mozilla will add support for Microsoft Silverlight to 64-bit versions of the Firefox browser on Windows in Firefox 43 or 44.

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  1. just a user said on January 19, 2016 at 7:43 pm

    I loved using sumatrapdf on 64bit firefox (I used a custom build) now no 64bit plugin (like vlc) loads, they should let users decide what plugins to use or not

  2. Jeet Chowdhury said on January 10, 2016 at 3:44 am

    Firefox should white list Java plug-in as well….

  3. jj said on November 30, 2015 at 6:30 pm

    I just use Cyberfox. It is 64 bit and accepts all adons and plugins.

  4. John said on November 27, 2015 at 4:15 pm

    MS Silverlight of all things… and to be removed again… why even bother if no other (current) browsers support it?

  5. 1 said on November 26, 2015 at 5:22 pm

    “That does not mean that they cannot protect their users by default, for instance by setting plugin contents to “click to play” instead of running them right away.”
    It is worth noting that when click to play is enabled websites are informed that you have the plugin(s) installed and often try to use them, even though they would just use HTML5 if you had disabled the plugin(s) completely.

    1. Tom Hawack said on November 27, 2015 at 5:31 pm

      Be click to play enabled or not websites know the plugins which are installed, and you are right about HTML5-ready sites that nevertheless require Flash once they “see” it is installed, even if click to play is used… and even if Flash has been disabled in the user’s browser (Firefox anyway). Amazing. I noticed sites that refused to play video with HTML5 when Flash was installed and disabled, but ran HTML5 once Flash had been removed (system-wide which included the Firefox Flash plug-in).

      This means that we may not conclude that because a site requires Flash (when disabled) it means it cannot run with HTML5. It may really run only Flash as it may not. You only know for sure once Flash is removed… or by asking around you.

      Not really surprising when you know the amount of information Flash provides concerning the user if Flash’s mms.cfg hasn’t been modified, compared to HTML5.

      Flash is eradicated here.

  6. 1 said on November 26, 2015 at 5:19 pm

    “This ends support for Flash, Silverlight and other browser plugins that depend on NPAPI in all versions of the Firefox web browser.”
    You had previously said “There is one exception to the rule and that is Adobe Flash. While support for all other NPAPI plugins is being removed in Firefox at the end of 2016, support for Adobe Flash remains available after that date.”

    1. Martin Brinkmann said on November 26, 2015 at 5:32 pm

      Well spotted. It seems currently that Flash will be supported while all other plugins won’t be.

  7. jasray said on November 25, 2015 at 5:32 pm

    The recent messages from Amazon Prime indicate a full move to 32bit HTML5–64bit and Silverlight is no longer supported.

    “To watch Amazon Video on your computer, we recommend using a browser that supports our HTML5-based web player.”

    For me, Silverlight hasn’t been an option in Settings; I’ve been required to use the Amazon HTML5 Web Player which renders video horribly–it’s a constant blur and focus, blur and focus [and, yes, my Internet connection is fine]. This is a new move by Amazon, and I am sure many will complain as loudly as those with Windows 10 November update problems.

    Always makes me wonder how companies define a “progressive” movement in an area of technological breakthroughs.

    Not long ago, however, on Ghacks, Silverlight was trashed by readers, so I figure maybe the new HTML5 move will make up for Windows 10 and Edge.

    1. Tom Hawack said on November 25, 2015 at 5:59 pm

      No visual problems here with HTML5, except perhaps a constant lack of contrast, ratio light/contrast still not very good. Flash definitely renders a better image at this time, but the difference, slight as I notice it here, is not sufficient to endure the everlasting, problematic, continuously updated for security reasons, permanently opened to attacks Adobe Flash player. Concerning Silverlight, I’ve never used it, or perhaps installed it once, back on XP, to follow the French Tennis tournament (Internationaux de Roland-Garros) but insufficiently required by sites to have it after that.

      HTML5 will improve. The idea of an autonomous browser is enough for me to support a slightly lesser video quality for the time being.

  8. Ann said on November 25, 2015 at 4:35 pm

    I’m running Windows 10 (w/ Microsoft Silverlight) and have a 64 bit operating system. I want FireFox to be my web browser (not ‘Edge’). I am not computer literate AT ALL.

    I’ve been using FireFox 42(?). The issue I’m having is watching YouTube videos. They just get stuck ‘loading’ when I attempt to play them. Another issue – If I go to the webpage of my local news station, those videos clips will not play at all…’s just a black box.

    What the hell???! I’ve been dealing with this mess for ages. What is MS Silverlight? What version of FireFox do I need to download with which flash play & plug-ins? Do I need to disable any plug-ins? I tabbed into your archive link in the above article and have no idea how/what to download from there. I don’t speak ‘html5’ or ‘NPAPl’ nor do I care. Just tell me where to go, what to download, enable or disable, in order to be able to seamlessly play YouTube and other sight videos. I’d really appreciate any help. Thanks!!!

    1. gdgssdgsd said on November 27, 2015 at 1:09 pm

      Get the latest version on Adobe Flash:

      Also to protect yourself from exploits you should get Malwarebytes Anti-Exploit, it’s free and you just install it and forget it it will automatically protect your browser and plugins (such as Flash):

    2. Andrew said on November 25, 2015 at 6:30 pm
  9. Tom Hawack said on November 25, 2015 at 3:31 pm

    I don’t use Silverlight, no more than Adobe’s Flash, I am of those who believe that html5 (browser capability to manage audio and video) is already a reality and fulfills tomorrow’s browser aims.

    I dislike the dilemma between audience and progress imposed by reluctant sites to adopt latest technology. I believe browser developers should impose the natural course of technological evolution to websites and their administrators. I’m not a radical but there are times where a choice is incompatible with consensus. We are dealing with evidence, not with gadgets seemingly dressed up with a pseudo-improvement attitude in order to legitimate what is or can be an intrusion and/or a degradation of users’ liberty : NPAPI must no longer be supported, even as a “tolerance” interval to allow sites to move their a*s. Period.

    I’m running Firefox 42 64-BIT and, if I use 64 (!) add-ons, I have not one plug-in installed. Beware of plug-ins. Easier to be aware on a 64-BIT browser since many if not most plug-ins have no 64-BIT declination (yet) and that is, as far as I’m concerned, the last of my worries.

  10. Ben said on November 25, 2015 at 3:26 pm

    But why?
    All those sites using silverlight had to migrate anyway because of chrome, so there is no need for it anyway.

  11. Maelish said on November 25, 2015 at 3:23 pm

    Any idea how hard is it to migrate from 32 bit to 64 bit?

    1. Ben said on November 25, 2015 at 3:28 pm

      1) You download the 64-bit installer.
      2) You double-click the .exe.
      3) You click three times on “next”. (well maybe four times, I didn’t check).

      1. Maelish said on November 25, 2015 at 5:06 pm

        And it migrates your plug-ins?

      2. Martin Brinkmann said on November 25, 2015 at 5:26 pm

        It does not migrate, it uses the same profiles you already have on your system.

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