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A fix for Java applets not loading in Firefox

with 23 comments

Although I’ve been running Windows 7 betas on and off periodically since the release of build 7000, it wasn’t until I used the x64 RC more extensively as my primary OS that I realized Java wouldn’t load in Firefox. Intriguingly, however, it appeared to be working just fine in both IE and Safari. I can’t say for sure how widespread the issue is, coming straight XP, however, my girlfriend’s laptop running Vista Ultimate x64 also faced the issue.


There were no manifestations of an actual error, in fact, Java applets were as blank as could be, and trying to interact with the Java console in Firefox caused the text to gray out with absolutely no result. All the while, Java’s plugin was listed in the browser’s add-ons, just as one would expect it to be.


My initial instinct sent me hunting through Firefox’s options to ensure that Java was enabled – which it was. I checked the Java control panel in Windows for any potential discrepancies, of which I found none. I naturally turned to Google as well as some Firefox and Java help documents, and came up empty handed.


Losing faith in my ability to use a search engine after a frustrating 30 minutes of seeking an explanation to what I expected would be a common issue, I dove into the programs files. Following a brief session of skimming Java file descriptions, I discovered two little gems: npjpi160_13.dll and npoji610.dll. Sharing a similar name, both are described as plugin files for the Netscape Navigator browser. Sure enough, a peak in Firefox’s plugins folder confirmed that both were missing.


The fix: Ensure that the latest copy of Java and Firefox are installed (watch out for the Yahoo! toolbar during installation). Navigate to Java’s program directory, and in the “bin” folder locate the files named “npjpi160_13.dll” and “npoji610.dll”. Copy both files and proceed to Firefox’s plugins folder, where you’ll paste them.


Assuming you’ve copied the proper files, and that this was the source of your issue, all should be well.


Armed with the file names, I was able to find potential bug recognition at If you’re still experiencing issues, visit Java’s Help Center for troubleshooting tips, and if necessary, feel free open a thread on our forum.

Written by Matthew DeCarlo

May 20th, 2009 at 7:27 pm

23 Comments so far

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  1. been having this issue on my laptop which came with 64 bit vista home premium, and now is running 64 bit windows 7. so i take it, it’s an issue for 64 bit computers. thanks for the fix!

    i actually never tried to fix it or find a fix, as the only time i’ve ever needed java was while trying to upload multiple photos on facebook. and for some reason it wouldn’t work and after a few installs i just gave up and uploaded the pictures one by one. my girlfriend will be happy about this.

    hopefully this will come to the attention of sun microsystems so they can fix the installer.


    21 May 09 at 9:19 am

  2. @Matthew: Thanks for posting the fix for this annoyance


    21 May 09 at 9:37 am

  3. You’re welcome. Hopefully it solves a lot of headaches.

    Matthew DeCarlo

    21 May 09 at 9:53 am

  4. The bug you link to is actually quite old (12-MAR-2007)

    According to the bug one of the causes is blamed on Mozilla’s registry entries being different from one version of its browser to another.

    – BrowserJavaVersion issue root cause:
    The problem with BrowserJavaVersion key is not a regression in our code, rather it is caused by changes in Mozilla’s treatments for its registries which we depended on:

    So who is to blame? Mozilla for frequently changing the registry structure of their browser or Sun for failing to keep their code up to date to properly detect Firefox?

    Ironically this is mentioned twice in the bug:
    please NEVER do any dll copying to workaround the problem.

    Presumably because the next Java update will likely fail to install/update the plugin requiring that it be manually copied again.

    Your article has java not working at all so IMHO at least there IS a workaround to get it working until someone decides how to fix this bug once and for all


    21 May 09 at 10:40 am

  5. Right – that two year old bug is the only faint hint of an official recognition that I was able find. It may or may not be 100% related to the current issues people like you and I have been experiencing.

    And yes, periodically you probably *will* have to recopy and paste the .dll’s.

    Matthew DeCarlo

    21 May 09 at 11:20 am

  6. Hi.

    Tanks for a this FIX. A have this issue and you helped me ! Tanks !


    3 Jun 09 at 1:19 am

  7. Matthew!! Thank you so much for this fix, it was driving me nuts to have to use IE for java – keep up the good work


    7 Jun 09 at 7:58 am

  8. Woo, it works! This is very much appreciated. :)


    9 Jun 09 at 3:44 pm

  9. I tried all this, but the only Java applets on certain sites will load up is if I either use Firefox in full safe mode, or use IETab. Yes, I have the np*.dlls in the plugin directory, yes, the sites are whitelisted for both NoScript and AdBlock, but still won’t launch the applets.


    6 Jul 09 at 1:07 am

  10. Superb!! That solved that problem on my Win 7 RC 64-bit!! Thanks!!


    13 Aug 09 at 12:31 pm

  11. Great fix, this issue is still very much present in the latest version Firefox on Windows 7 RC 64bit

    It had been driving me mad!



    1 Sep 09 at 2:21 pm

  12. You’re right about the documentation – nothin’. I upgraded to Ultimate 64 bit and this problem kicked in. Fix works great, thanks!


    9 Sep 09 at 9:17 pm

  13. I found that this also works for 32-but XP too! Thanks


    1 Dec 09 at 3:20 pm

  14. Thank you so much. It took me 9 seconds to do the fix and it worked.

    Alan Robinson

    10 Dec 09 at 2:58 pm

  15. Thank you so much for this fix. I have been dealing with this problem since I received my laptop. Thank you!


    16 Dec 09 at 9:26 pm

  16. Thanks for the Java fix Matthew! It worked for me and solved the problem in one minute. Windows Vista and Firefox 3.5.6.


    26 Dec 09 at 7:43 am

  17. Thanks alot for that fix. Works like a charm!


    2 Jan 10 at 1:48 pm

  18. You rock… I was pulling my hair out and your fix worked… XP Firefox ver 3.5.7 Java 6


    18 Jan 10 at 2:57 pm

  19. I had this issue with IE8 32-bit and 64-bit,
    Firefox 3.0.1 and 3.6.3 32-bit, and also Minefield
    (Firefox 3.6.3) 64-bit on my Toshiba Satellite A505-S6979 laptop running under Windows 7 6.1 Home Premium 64-bit with installed jdk-6u19, both 32 and 64 bit.

    None of the browsers displayed applets and 64-bit browsers displayed blank web pages.

    Tools>Add-ons and about:plugins for all the browsers showed the “next-generation Java Plug-in installed.

    Windows Control Panel>Programs showed an icon for “Java”. Under this link > tab Advanced
    the Settings tree, Java Plug-in item had a check box
    for option “Enable the next-generation Java Plug-in”
    which was grayed out and impossible to uncheck.

    After having read about your fix on this page,
    I uninstalled both versions of Java and first re-installed the 32-bit version only.

    I went to the Windows Control Panel again and found there a different link to Java, pointing, this time
    to “Java 32-bit”.

    I opened this Java Control Panel and found that
    now I could uncheck the check box for “Enable the next-generation Java Plug-in” option, which I did.

    After that 32-bit browsers displayed web pages and applets correctly while 64-bit browsers displayed web pages but without applets.

    Firefox Tools>Add-ons list showed a different
    Java Plug-in as installed. This time it was the
    “Classic style” Java Plug-in.

    These were apparently npjpi160_19.dll
    and npoji610.dll plug-in files.

    In the next step I re-installed Java jdk-16u19 64-bit.

    Now all the browsers (32-bit and 64-bit) display web pages and applets correctly. The Firefox Tools>Add-ons list again only the “next-generation Java Plug-in” as installed.

    The Windows Control Panel again shows a link to
    “Java” only and, as previously, the “Enable the next-generation Java Plug-in” option, under the Advanced tab, is grayed out.

    Everything works as it is supposed to.


    15 Apr 10 at 10:14 pm

  20. This fixed my issue thanks. Running xp sp3/32bit..ff v3.63 btw.
    I realized I had a problem when I was doing a cross browser check on a website I’m building and java app wasn’t working in ff only…
    The only change I made in ff was that I installed Google toolbar and removed the bookmarks toolbar…if that’s any interest.

    Thanks Again!


    22 May 10 at 6:01 pm

  21. This fix is still valid. I’m running xp pro, sp3, latest java firefox 3.0.18.
    I would only get the Java loading image, and could never get java to work, or only partially.
    I did a search for npoji*.dll and npjpi*.dll and copied the latest versions found to my Firefox/plugins folder, and restarted Firefox.
    Voila !!! all things working as they should now.

    Thanks for keeping this thread up :)


    22 Jun 10 at 10:36 am

  22. I’ve been having this problem too for a while. I’m glad I found your post! It’s such a weird issue, because both Firefox and IE seemed to think Java was installed, but it obviously wasn’t!

    This was on Windows 7, IE 8, Firefox 3.6.6.

    Nick B

    1 Jul 10 at 3:44 pm

  23. Thank you thank you thank you thank you thank you thank you thank you thank you thank you thank you thank you thank you thank you thank you thank you thank you thank you sooooooooooooooooooo much!!!!!!!!!!!!!!!! Now my java works again!!!! Thank you!!!!!!!!!!

    Eve S

    20 Aug 10 at 2:53 pm

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