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Turning Java plugin on or off in Firefox web browser

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Enable or Disable Java in Firefox

Beginning in Firefox version 52 released March 7, 2017, installed NPAPI plugins are no longer supported in Firefox, except for Adobe Flash. Some of the plugins that will no longer load in Firefox, even though they may be installed on your computer, include Java, Microsoft Silverlight and Adobe Acrobat.

Over the past few years, Firefox has implemented various Web APIs so that websites can do the same things they’ve always done without plugins, so you will most likely not notice any change to your browsing experience.

Older versions of Firefox:

  • Click on the Menu button in the top right corner
  • Click on "Add-Ons" - it is the option with the puzzle piece icon
  • On the left select "Plugins"
  • Find the Java plugin that you have installed - Will most likely begin with "Java(TM) Platform"
  • In the drop down menu select "Never Activate" to disable Java. Select "Always Activate" or "Ask to Activate" to enable Java


Always Activate vs. Ask to Activate

"Ask to Activate" will prompt the user with a dialog box, asking if they want to use Java, every time the browser attempts to run the Java plugin. Choosing "Always Activate" will skip this dialog box and automatically use the Java plugin whenever it is called.

Older versions of Firefox (Mac):

  • Click on the Tools menu at the top
  • Click on "Add-ons"
  • Click on "Plugins"
  • FInd the Java plugin listed on this screen.    For Leopard and Snow Leopard ( Mac OSX 10.5 & 10.6), this plugin will be called "Java Plug-in 2 for NPAPI Browser."  On Lion (Mac OSX 10.7), this plugin will be called "Java Applet Plug-in.
  • Click on the "Enable" button for this plugin to enable it  OR click on the "Disable" button to turn off Java for Firefox


Java on Leopard and earlier versions of Mac OSX

Java contains a security hole that can lead to a malware infections such as Flashback on the Mac. A security patch to close this vulnerability on Leopard and earlier versions of the Mac operating system (patches for Java on Snow Leopard and Lion have been released).  For Leopard and earlier Mac operating systems, Apple is suggesting that users disable Java to better protect their machines (Apple Page on Flashback).  ITS recommends that you upgrade to Snow Leopard or Lion if you are running an older Mac OSX version.