When Firefox won’t launch Java applets
If Firefox won’t launch java applets, but Internet Explorer will, you may need to change some settings in the Java control panel to turn on Applet support for Firefox. (Expert users: One sign that this is the issue rather than some Java security exception is that the Java console will be completely blank when you try to launch the applet in Firefox. _
Unfortunately on many PC’s, the Java control panel can be a challenge to find. First, check in the control panels area for “Java.” If it is not there, you may have to look in
for JRE (Java Runtime Environment) folders.
In the image below there are several of them. Usually you should pick the most recent one, as that is the one that is probably in use.
Inside the jre[xx] folder, you will find a “bin” folder. Inside that, click on either javacpl.cpl (may not exist in earlier versions) or javacpl.exe. The Java Control Panel will open.
Click the Advanced tab. Depending on which version of JRE you have, you may see “Applet Tag Support” (earlier versions)
or Default Java for browsers (later versions).
Expand whichever one you see, and look to see if Mozilla family (or Mozilla and Netscape) is checked. If not, check it, click “Apply” and restart Firefox.
You may have noticed that the Java console settings are in the same tab under “Debugging. Check all three items under “Debugging” to turn on the Java console and have it launch whenever Java is called in the browser so that you can see what’s happening.