Firefox on OS X: Java not working?

Jan 25, 2011 One-minute read

<img class=“alignright style=“margin: 5px;” title=“Mozilla Firefox” src="/images/2011/01/firefox-logo-wordmark.png” alt=“Mozilla Firefox” width=“200” height=“76” />With recent Firefox versions (3.6, 4.0 beta), I was unable to view any kind of website that uses Java on my Mac.

Browsing through the about:plugins{.liinternal} page I found out that I had three different versions of the Java Embedding Plugin (MRJPlugin.plugin) loaded in Firefox — two of them in addition to the one that already ships with Firefox!

The additional add-ons were found in

  • /Library/Internet Plug-Ins
  • <user>/Library/Internet Plugins/

After deleting those and restarting Firefox, I was able to enjoy the beauty of Java applets again!1