1320381 - Plugins are no longer detected on firefox 50, even though they are all set to always allow.

Status: RESOLVED DUPLICATE of bug 1317846

(Core Graveyard :: Plug-ins, defect)

Description

[Karel Karlik]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0
Build ID: 20161119214345

Steps to reproduce:

I upgraded firefox to version 50, and now plugins (specifically, adobe flash) are no longer detected by sites that use them. Not even by the plugin check site.
The plugin is definitely installed and enabled - I can play flash files from internet.

about:plugins says this about flash (there are also openh264 (enabled), java (enabled) and gnome shell integration (disabled) plugins before it, in that order):
Shockwave Flash

    File: libflashplayer.so
    Path: /usr/lib/adobe-flashplugin/libflashplayer.so
    Version: 11.2.202.644
    State: Enabled
    Shockwave Flash 11.2 r202

MIME Type	Description	Suffixes
application/x-shockwave-flash	Shockwave Flash	swf
application/futuresplash	FutureSplash Player	spl

about:addons says that (in that order)
openh264 - always activate
shockwave flash - always activate
java - always activate
gnome shell integration - never activate

I have the flashblock addon, but I have it in "disabled" mode for testing this (the addon itself isn't disabled, but it is set to not tamper with flash content), and it didn't cause this problem in firefox 49.


Actual results:

navigator.mimeTypes["application/x-shockwave-flash"] == undefined
navigator.plugins['Shockwave Flash'] == undefined


Expected results:

return the cirrect MimeType and Plugin objects, respectively

Comment 1

[Karel Karlik]

Some sites won't even include the flash object if they don't detect the plugin, so this actually breaks them for me.

Comment 2

[Loic]

Does it work normally with a fresh profile?
https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

Comment 3

[Karel Karlik]

It works normally in a different profile (it's not even fresh). Console:
navigator.plugins
PluginArray { Gnome Shell Integration: Plugin, Java(TM) Plug-in 1.6.0_26: Plugin, Shockwave Flash: Plugin, length: 3, 3 more… }

This profile still has empty navigator.plugins, even with safe mode.

Comment 4

[Benjamin Smedberg]

Do you have the privacy.resistFingerprinting pref set?

Comment 5

[Karel Karlik]

Yes. It was set to true. Toggling it off gets navigator.plugin and navigator.mimeTypes populated again.
Is that how it's supposed to work? I got the impression that the arrays should be empty, but querying navigator.plugins.namedItem('Shockwave Flash') was still supposed to return something?

Comment 7

[Benjamin Smedberg]

Please see bug 1281963 for details.