Firefox 34 - Black screen playing Adobe flash videos

Question

After upgrading to Firefox 34, Flash videos stopped working. A black screen was presented, with no hint to the problem. Following these instructions and these other instructions, would prove futile.

Setting YouTube to playback using HTML5 also did not resolve the problem.

Solution 1

The Flashblock add-on is incompatible with Firefox 34; remove the add-on.

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The following might work (untested):

1. Start Firefox and press Alt+h to open the Help menu
2. Press t to select Troubleshooting Information
3. Click the button for Open Containing Folder (or Open Directory)
4. Create a folder (directory) named Chrome
5. Create a new file named userContent.css
6. Copy the following text into the new file:

   /* Flash Block */
   @namespace url(http://www.w3.org/1999/xhtml);
   @-moz-document domain("youtube.com"){
   #theater-background { display:none !important;}
   }

7. Save and close the file
8. Restart Firefox

Solution 2

Solved for me : I just removed the "Adobe flash player" installed through the Ubuntu software center. It may conflict with the firefox flash plugin Firefox and chromium OK

Comments

[John Scott]

For one, Flash 11 works fine with YouTube. Second, YouTube uses HTML5 in FIrefox by default. THird, Adobe still does make updates for the GNU/Linux version of their flash player.

[Sudheer]

@FuzzyToothpaste adobe flash 11 initially worked fine for me but after updating the firefox to latest versions it stopped working. youtube uses html5 but what about other sites which you adobe flash they will still be black screen. third please read my answer carefully i did not mention about any adobe updates released for linux.

[John Scott]

I did read it carefully and the very first sentence says "Since Adobe flash plugin 11, there are no adobe flash updates available for firefox in linux."

[Skippy le Grand Gourou]

Anyway the solution preconised by Sudheer worked like a charm on a fresh 14.04 install where adobe-flashplugin from "partner" repository did not help.