I've got Mozilla Firefox 64-bit running on Windows 8.1 with the latest Java (both 32 and 64-bits versions) installed on my computer.

Recently I uninstalled and re-installed Firefox on this computer, and Java no longer shows up in Plugins in about:addons, and websites needing Java no longer work...

What can I do to make Firefox detect my Java installation again? Thanks!

  • I believe it has always been recommended that users use 32-bit firefox. – Frank Thomas Dec 4 '16 at 20:09

It would appear that Java is blocked in Firefox 64-bit.

From: Mozilla Blog: Use the Java plugin to view interactive content on websites

Mozilla plans to drop support for all NPAPI plugins except for Flash in March 2017, when Firefox version 52 is released.

Note: The 64-bit version of Firefox does not recognize or support this plugin.

Also from Mozilla Forums: No Java plugin

Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:43.0) Gecko/20100101 Firefox/43.0

You have the 64-bit version of Firefox, where only Silverlight and Flash Plugins are 'whitelisted'. If you need Java you need to install the 32-bit version of Firefox. You can have both the 64-bit and 32-bit versions installed, but you'll need to do a "custom" installation (on the first screen of the installer routine) and select or create a uniquely named folder - like maybe Firefox 32, otherwise the 32-bit installer may overwrite your 64-bit Firefox installation.

This is probably due to the ongoing drive to eradicate insecure and NPAPI-based plugins.

From a security standpoint, this is A Good Thing (tm), but from your standpoint you need to use a 32-bit version of the browser.

  • Ah yes, that did it after I installed the 32-bits version. Thank you for the information! – hpy Dec 5 '16 at 2:48
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    @hpy Glad that fixed it for now, but just bear in mind that come March 2017 it will likely break permanently and may never come back... – Mokubai Dec 5 '16 at 8:09
  • Thanks for the warning. In preparation for that is there another way to get Java working in Firefox? Or is it simply that Java will never be supported in Firefox again after that time? – hpy Dec 12 '16 at 15:39
  • @hpy I had a look last night and it doesn't appear to be a replacement for the NPAPI that Java would use to talk to Firefox. Chrome has moved to PPAPI, but Java would have to be updated to support that. Other than that the only answer I can find is either "get rid of your junk that needs Java" or "use another browser." It's possible that one of the Firefox derivatives might continue to support NPAPI, but I doubt it will carry on forever. – Mokubai Dec 13 '16 at 12:35

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