Documenting Problems That Were Difficult To Find The Answer To

How Do I Get Java Working On Firefox 16 With Windows 7 64-Bit

This was driving me crazy. I upgraded to Firefox 16 (from 15) and all of a sudden Firefox wouldn’t run Java-based websites.

Mozilla explain that this is because the previous version of Java installed on my computer was deemed “insecure”.

So: here’s what to do.


Make sure all browsers on your desktop are closed.

Download and install Java 32-bit (even if you’re on a 64-bit Windows 7 machine) from the manual download page on


Start Firefox. Then select from the menu (you might have to press the Alt key to make the menu appear):

  Tools -> Add-Ons (also ctrl-shift-A will do the same thing)

Next find the Java plug-in (not the Java Deployment Tool which is completely unrelated) from the list of plug-ins. It might be at the bottom of the list.

Press the Enable button. Yes: you have to tell Firefox that you want to run Java again because it (unhelpfully) disabled the plug-in!

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