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How to always enable Java 6 with Firefox 18


I implemented Firefox 15 with Java to be used with a particular Vendor's website. The site has no internet except for accessing this vendor's website. Several weeks ago Firefox 15 updated itself to Firefox 18 and blocklisted Java 6. I was able to unblock it, but now each time the users log into the vendor's website, Firefox prompts the user to activate Java 6. My users are nagging me to turn this activate screen off but i cannot figure out how to permanently activate Java 6 on each of these machines. The vendor is not willing to upgrade to Java 7. I have tested Java 7 with the vendor's site and of course it doesn't load. Consequently, I cannot get this machine to roll back to Java 6. Once they activate Java 6 they can use the website. I could switch back to IE8 and use Java 6 with no problem, except that IE8 has a flaw in it. I have read that I cannot install IE9 on Windows XP pro, so I am stuck with Firefox. Windows XP Pro SP3, Firefox 18, and Java 6.

Additional System Details

Installed Plug-ins

  • Shockwave Flash 11.5 r502
  • Adobe PDF Plug-In For Firefox and Netscape 10.1.5
  • Next Generation Java Plug-in 10.9.2 for Mozilla browsers
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Adobe PDF Plug-In For Firefox and Netscape 10.0.1
  • The plug-in allows you to open and edit files using Microsoft Office applications
  • Office Authorization plug-in for NPAPI browsers
  • Windows Presentation Foundation (WPF) plug-in for Mozilla browsers


  • User Agent: Mozilla/5.0 (Windows NT 5.2; rv:19.0) Gecko/20100101 Firefox/19.0

More Information

  • Top 10 Contributor
  • Moderator
2046 solutions 8901 answers

you could set extensions.blocklist.enabled to false, but use it at your own risk...


Modified by philipp

David Tenser
  • Administrator
  • Moderator
32 solutions 294 answers

Helpful Reply

Hi there,

This article walks you through how to enable Java again -- note that we don't recommend this due to the many security risks (this week new threats were revealed again): How to allow Java on trusted sites

Hope this helps!

Cheers, David

  • Top 10 Contributor
  • Moderator
10762 solutions 96861 answers

Is this the Firefox window that the Java plugin is blocked or is this the security pop-up from Java asking for permission?