Oh I should also mention that java runs fine in Internet Explorer, although that browser makes me cringe...so it's something on the side of Firefox.

Try turning off the AdBlock if you have it installed. For me it worked.

i had java 1.6.0.24 (64bit) and firefox 4 (beta, RC) installed on win7 (64bit), but java plugin didn't show in plugins section and java of course didn't work; i uninstalled both, java and ff, and installed java 1.6.0.24 (32bit); now java is working on ff but not on ie (64bit), for that you need 64bit version of java, i guess; the problem is, that win7 64bit installs firefox in "c/program files(x86)" folder, but 64bit version of java is installed in "c/program files" folder;

java also works with adblock enabled (easy list+easy privacy)

hope that helps

might be helpful for some, I'm only using Windows 7 32 bit though

i'm not very familiar with win7 (32 or 64bit) yet, because i mostly use ubuntu, but here are some other suggestions that might help:

a) install java BEFORE installing firefox (if you haven't done that already); b) run java control panel (control panel>programs>java) and enable "mozilla family" under "default java for browsers" and/or try to disable the next generation java plug-in under "java plug-in"; c) check in firefox (tools>ad-ons>plugins) if java is enabled; d) if all else fails, check this link: "https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins" (and perhaps other related pages, java.com for example).

wish you luck

Install Java 1.6.24(available on filehippo). Works both with IE 9 and Firefox 4 Beta, RC. Just be sure to Close Firefox instances before installing this JRE update, because the installer dosent recognise this version of firefox and doesnt close it.... Enjoy!!

Okay I have tried clean installations of both Java and Firefox, to no avail (even installing java first as recommended somewhere)

I'm thinking it is more a java issue, I tested Google Chrome to see if java would work in it, but it has the same issue where it doesn't recognize java unless run as an administrator.

Does anyone have any idea why java would have such permission issues?

Hopefully this will help: If you're running on a 64-bit machine, use the 32-bit JRE and not the 64-bit version. For reasons which remain unclear, the 64-bit JRE fails to recognize Firefox. Perhaps it's because Firefox itself is a 32-bit app. Who knows.

-Damon

I know all the people that are sending tweeks etc are trying to do the right thing, but there is a fundamental problem with firefox 4. Java doesnt work! It used to work in Version 3.xxx now it doesnt and Mozilla need to get it fixed. If they dont IE9 will win the game!! I have been a dedicated user of firefox for about 3 years now(might be shorter) but in that time I have never had so many problems as this new version. My webmail client no longer works, BBC iPlayer doesnt work etc... get a grip on you problems developers, I dont need tweeks I need a fix!

All above seem to be Windows. I am on Linux Fedora 13 64 bit. Same Java issue as above. I still don't have resolution but can work on it. Is this addressed in another thread? Hard to believe this is really an outstanding issue, no Java ???

Anyway, Firefox 4 is just dynamite, really fast and pretty stable for me. What a product. This is replacing my Chrome experiment.

IE ? Sometimes I have to bring up a VMWare image for applications with IE dependencies. GIVE ME A BREAK. Developers/designers get on the ball and remove those dependencies.

Firefox is a 32 bit program, so you need to have 32 bit Java installed and make sure that Firefox can find the JP2 plugin (Linux: libnpjp2.so; Windows: npjp2.dll).

See:

• http://kb.mozillazine.org/Java

I checked my java version through internet explorer, it said I have 32bit. Java is listed as a plugin, but some how mysteriously does not work...lol, unless run as admin of course.

Maybe a possible work around would be changing the permissions of a certain java file the browser uses? the same issue occurs in chrome, so its not only FF, as I said before.

You can try:

Control Panel > Java > General tab > "Network Settings...": "Direct Connection" (enable)

Direct connection didn't work either

Updating Java to 6.0 update 25 fixed my issues, Java works great now. If you only have 64 bit Java installed, installing the 32 bit version in addition to the 64 bit version of Java may help you.

Unless you're doing some crazy Java stuff, the 64 bit version should not provide any improvements; it just leads to headaches. If you really need 64-bit, you can have both 32 and 64 installed at the same time as I do. I've done this since I started using Windows 7 RTM quite a few years ago... when lots of things had issues with 64-bit Java (including Eclipse IDE.)

//m

Maybe some of your problems originate from the fact that you need to use a different java plugin compared to the 3.xx versions

see:

http://linuxcoaching.ie/linux_coaching/2011/04/the-new-java-plugin-for-firefox-4.html

Same with 32-bit Windows XP.

Java plugin (1.6.25) works perfectly when connected under an Administrator account. When connected with my personal account, without administrative rights, the plugin doesn't even appear in the plugins list. I have AdBlockPlus enabled in both profiles.

I have never seen that behaviour with FF3.

Note : I share the same personal FF profile with my Linux account, and the Linux Java plugin works correctly. So this is a FF for Windows problem, and it's not 32 vs 64 bit related.

I got mine working by disabling mozilla plugin and enabling next generation java plug-in in java control panel