Firefox Java hanging workaround

Recent updates of Firefox and Java don't tend to play nice. I've had existing JRE 6 installations that were fine but then Mozilla adds these JRE versions to their vunerablity blocklists.

The net result is that the previously working Firefox/JRE plugin combination now hangs and crashes Firefox (Windows 7 x64). The same plugin works in Chrome. I hate poorly implemented upgrades.

The most recent occurance of this problem was with Firefox 21.0 and JRE 6u45. These components worked fine until JRE 6u45 was added to the Mozilla blocklist as being vunerable and out of date (Firefox periodically pings a Mozilla service to obtain a list of vunerable plugins). After this point whenever Firefox hit a java enabled page, it would lock up. Marvellous.

Upgrading to JRE 7u25 had the same lock/crashing problem. Jumping up to Firefox 22.0, same problem with both JRE 7 and 6.

The only workaround I found was to disable the Mozilla blocklist feature within Firefox.

about:config
-> extensions.blocklist.enabled = false

With this, Firefox 21 and 22 now work fine with JRE 6. Please note this is a workaround for something that Mozilla should fix - anyone going with this workaround will need to worry/take manual actions to ensure they upgrade any vunerable plugins (Adobe Flash etc).

Furthermore, some later updates of firefox seem to ignore the long used firefox installation's plugin dir (ie /usr/firefox/plugins) which means that firefox won't even find ANY of your plugins. The problem results from the config value plugins.load_appdir plugins defaulting to a value that means the installation's plugin dir is not loaded.

However, some users -- Linux x86 NVidea + flash -- have perpetual bugs that have been reported but been noted by the developers (adobe) as not to be fixed. Thus, such workarounds are actually needed.