Firefox and Java JRE update problem fixed

This article was originally published on 28/03/2005.

Firefox browser could not display Java applets following a recent upgrade to the Firefox browser and the Java JRE. A simple solution found.

A little background to this story. As a devout convert to the Firefox browser, I immediately upgraded to the latest release, Version 1.0.2, when it became available. Shortly after upgrading the Firefox browser I found I was unable to access my internet banking account, and was displayed a standard message from the internet banking service that my browser did not have Java installed. Necessity forced me to use IE, which worked with no problems. I had also accessed the internet banking account through Firefox only a few days previously, so there was something wrong with Firefox!

I dutifully checked my browser settings and Java was enabled. I then checked the Java control panel and noticed that the option to use Java with Mozilla/Netscape was unchecked. Found the culprit? Unfortunately not. After checking the option and pressing apply, I was informed that the action could not be completed as I did not have sufficient rights to change the browser settings. Now this was a concern, as I am administrator, super-administrator, and any other kind of controlling power over my pc, or so I thought.

Time to start on a solution, so Google in hand I went on a wild search for others who had faced the same problem. It would seem that this is a reasonably new problem (at the time of writing), as very few results were returned. Those results that were on-topic offered a selection of causes/solutions, none of which worked for me. As a result of trying each solution in turn, and scouring through the folders and files associated with both Firefox and Java, I did find what was the apparent cause of the problem in my case. On the latest update to the Java JRE, the Java Plugin dll had not been updated in the Firefox plugins folder. On a whim I renamed the existing Java plugin dll and fired up Firefox again, and hey presto, everything was working. Now I don’t know why the original dll had not been updated, but it hadn’t, and I don’t know if this solution will work for everybody, but it did for me, and I offer this advice in the hope that it can help somebody in the same position as I found myself.


  • Unable to view Java applet content in Firefox browser


  • Upgrade of Java JRE to version 1.5.0_02 does not update Java plugin dll in Firefox plugins folder


  • Delete previous Java plugin dll file NPOJI610.dll from Firefox plugins folder.
  • Prior to deleting the file I would suggest renaming the file (zz_NPOJI610.dll) to test that this solution works for you.

Machine Spec:

  • Windows XP Pro SP1
  • Firefox 1.0.1
  • Java JRE 1.5.0_02

61 comments on “Firefox and Java JRE update problem fixed

  1. WTF? I have been a loyal Firefox fan and understand diff between commercial software and Mozilla. But this does not sound like an obscure bug and I am getting similar messages in February 2010. I have seen similar discussions of same topic from late 2006. Why is this not fixed by Mozillar and/or Sun(Oracle) Java?
    I have latest versions of Java and Firefox. I can’t find trace of Java Console in the plugin lists or in my Control Panel list of Add or Remove Programs.
    When I search I find ten copies (!) of NPOJI610.dll in various Java directories. Apparently when Java updates it simply creates a new directory and a new copy of everything. How strange is that. I wonder why they are the only program install that is too lazy to uninstall or at least write over the old version.
    I will uninstall all my old versions of Java and then install again from scratch. I hope that works.

    1. Please let me know if that worked for you..I currently have about 5 versions of Java and was afraid to uninstall them and start all over with the most current…….Please advise… Thanks

  2. I THINK THE LOGICAL THING IS SOMEONE TELL ME A NEW BROWSER WITHOUT JAVA problems i am not liking firefox so much anymore at all

  3. i need help of you all great people.
    i am using firefox 3.5.1 and one java applet icon is not appearing. what should i do i have jinit and jaa 6 11th update installed.

    please help.

  4. i have a problem with my firefox whenever i open a site it pops up a dialogue saying : “firefox doesnt know how to open this address,because the protocol (javascript) is not associated with any program… yet i have java enabled …i need some help

    1. Hi Martik, this sounds like the config settings in Firefox have changed. Follow the steps below to check/reset the settings.

      Note: the following steps require you to make changes to the internal workings of the Firefox browser. Messing around with the config settings can quickly get you into trouble and leave you with a bricked browser. You have been warned!

      1. Open firefox
      2. In the address bar type: about:config
      3. Read and accept the “here be dragons” warning
      4. In the Filter box type: network.protocol-handler.external.javascript
      5. The value here should be false. If it isn’t, double click the entry to toggle it to false.
      6. Open an new tab and visit a page with a javascript link on it to test. If all is good close the about:config tab. You’re done.

      Hopefully the above guide fixes your issue.

        1. I have the same problem and i have only had FIREFOX trouble recently as it seems a race for them to rush new F A S T E S T versions out to claim the FASTEST BROWSER …well i did what you mentioned and the value was false and i GET THOUSANDS of ERROR CONSOLE Errors listed as firefox says “just ignore them, they cause nothing…thats not true… they slow my system down and make my mouse operations spongey…..omg im about to throw this cup o java out help!

          tim in houston

  5. Hi.

    you need to help me! I forget already what did i done. But eclipse can be opened and any website that have a java applet that i surf make my firefox and IE stop working..

    But my java application doing well..I’m using vista, because of my pc enable to start, i thought there is something wrong, so i uninstall java(TM) 6 update 4 , 5, 7

    maybe because of that..please tell what to do.

  6. Hello all,

    I am hoping somebody can help. I cannot install the latest java update 1.6/6. I keep getting the message that” the installation of the update to the java platform was not completed. I am using firefox 2.0.14 …………..any ideas?


  7. Hello you fine people

    I’m using Vista Premium, Firefox and Java JRE

    I have tried all the advises from this thread, but Java is still not working in Firefox.

    Can someone tell me how to fix this issue.


  8. HI ALL
    I m using linux plateform,with firefox2.0 version(latest).
    I have jre installed on my comp. but still i m not able to see java applets window.
    Plz i will be very oblized if u can give me a solution.


  9. You are a wonderful and kind person lol. This has driven me absolutely mad for a couple weeks, and I’m embarrassed to list all the things that I’ve tried…that have all failed. Kudos and thanks!

  10. I just got a new laptop with Vista Home Premium and I didn’t find the dll in Firefox’s plugins folder. So I went to java’s site and downloaded the latest java here:

    At the moment, the latest is Version 6 Update 3.

    I didn’t have to delete or uninstall anything. I just installed the new java version and now I can connect to my web host’s Unlimited FTP site.

  11. i tried to uninstall firefox, update, reinstall java runtime,…etc.

    now just rename the dll file, and everything works fine 🙂

    Great job!

  12. After updating to java,if Igo to one particular web site I get a general exception error,firefox will not download any more and I have to reinstall it
    (every time ).I haven’t got a npoji___ .dll in firefox or java,and it’s only happened since.Has anybody got any ideas,Im lost. rob
    installing 1.6.Java Plug-in 1.6.0_03
    Using JRE version 1.6.0_03 Java HotSpot(TM) Client VM
    User home directory = C:\Documents and Settings\Rob

    c: clear console window
    f: finalize objects on finalization queue
    g: garbage collect
    h: display this help message
    l: dump classloader list
    m: print memory usage
    o: trigger logging
    p: reload proxy configuration
    q: hide console
    r: reload policy configuration
    s: dump system and deployment properties
    t: dump thread list
    v: dump thread stack
    x: clear classloader cache
    0-5: set trace level to

    java.lang.NumberFormatException: For input string: “#003366”
    at java.lang.NumberFormatException.forInputString(Unknown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at Marquee.init(
    at Source)
    at Source)
    java.lang.NumberFormatException: For input string: “#003366”
    at java.lang.NumberFormatException.forInputString(Unknown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at Marquee.init(
    at Source)
    at Source)

  13. I’ve been trying to figure this problem out for a LONG time. I just happened to come across your site and everything works fine now! THANK YOU!

  14. Shelly: I installed a wrong dictionary and after that I had problems with my java. Firefox was warning me about the German dictionary but I ignored the warning. Later I deleted the new Sun Java version ( the old one was workig ) did some reading on the Internet and they said that the new Sun Java version was not competable with Firefox and they look to fix the program. Many weeks later my Java did an automatic update and Firefox was working again. Try to update your Java. Try to update your Firefox too.
    Try this one ” I couldn’t find the file NPOJI610.dll in firefox/plugin folder. But I find it in my java/bin folder and copied it to the firefox/plugin folder. It WORKED!

    Do a search on your computer with:NPOJI610.dll
    Is it in your firefox plugin folder?

  15. I am not as computer literate as most of you…I have had a problem with java and firefox and would love a clear, step-by-baby-steps- approach to fixing this dll issue.
    Anyone want to help a poor soul 🙁

  16. According to “help” -> “Check for updates…” I have the newest Firefox installed, which “Help” -> “About Mozilla Firefox” tells me is Today the problem is still there (after so long time) on a Windows XP installation.

    I think the main problem is, that the file npoji610.dll can be found to places and not one place, which probably should be in the bin directory of the latest installed java runtime system. This would require some lookup functionality from Firefox – I would very much appreciate, if the team behind Firefox could do this.

    The “gold solution” would be, if it could be possible from: “Settings” -> “Control Panel” -> “Java” -> “Java tab” -> “View” button under “Java Applet Runtime Settings” to have a list of installed Java Runtime System from which one can choose (today not possible) the Runtime System they want (note that is possible under the JNLP Runtime Settings) – The customers of my company may have more than one Runtime System installed, but is typically not running the latest version of the Runtime System, which is what they are forced to use, so that would be a nice feature to have.

  17. >But then after I changed the firefox.exe file to be run as administrator (go to >properties – right click on the file), java works… just in case you encounter same >problem as me, this may be useful.

    That worked for me, which is strange because I was already logged in as an administrator.

  18. Hi I am facing a similar Java Error. Only this time the error is not displayed and only the applets never run.
    I am running XP sp2, Firefox 2.0, not sure about Java & Java Script version but I think its the latest.

  19. Installed some spell check plug ins and after that Java wasn’t working anymore.
    I do have the .dll ‘s in all folders.
    I have been reading somewhere that after a wrong made plugin that Firefox is not recognizing the extensions anymore.

  20. Trying to solve for hours. The post by JayZed avobe was the answer for me.
    running FF and Java 1.6.0 with Windows XP

    I couldn’t find the file NPOJI610.dll in firefox/plugin folder. But I find it in my java/bin folder and copied it to the firefox/plugin folder. It WORKED!

  21. got same problem. i use Vista, Firefox, Java runtime 6 update 1. After copying the dll from Java bin folder to Firefox plugin folder apparently it still did not work for me.

    But then after I changed the firefox.exe file to be run as administrator (go to properties – right click on the file), java works… just in case you encounter same problem as me, this may be useful.


  22. Amazing tip…thank you! I was experiencing the exact same issues under WinXP, Firefox2 and the latest JRE. I renamed the dll and voia la!

    Awesome…thank you thank you thank you!


  23. I couldn’t find the file NPOJI610.dll in firefox/plugin folder. But I find it in my java/bin folder and copied it to the firefox/plugin folder. It WORKED! THANKS SO MUCH for sharing your tip.

  24. I was having the same frustrating problem with firefox and java. Having just bought a brand new laptop running vista and the latest versions of everything this was very annoying. I tried the first tip on this page but I also found that the dll was not in the firefox plugins folder so tried the other tip someone left about just copying the dll from the java directory into the firefox directory now it works a charm. Thanks!

  25. for the most people that has npoji600.dll in the firefox pluggins folder it work, but somebody knows how to solve it in case that this dll isn’t there?

    In linux operating system the trick is really fast and point to add functionality to the firefox, why in windows the solution is to eliminate the link of firefox with the pluggins? if this dll are old and it isn’t compatible, that’s fine, but should be another dll that has the right functionality in order to firefox can run applets?

  26. To all that this write up has helped, thanks for your feedback.

    To all that haven’t been helped, I can only offer my sympathies. I know the pain you are going through. If you have since found a solution to your problems let me know and I will write a follow up to this post with a selection of alternative possible fixes.

  27. Config: Firefox and WinXP SP2
    I found npoji600.dll in c:\program files\mozilla firefox\plugins and renamed it as you say so. It works then and thanks.

  28. I’m running Vista and JRE !.6.0 and same problem as Lesch above, lugins don’t appear for Java in the FF plug-ins directory and copying and pasting don’t solve the issue either. I been troubleshooting this for hours and have checked and rechecked settings and Googled the issue to death.
    We need some help!!!

  29. Sadly, your tip does not work for me either. I had the same problem running Java apps in my Firefox ( in WinXP. Initially, I tried to verify my installation on the Java website but I got a runtime error “R6025 – pure virtual function call” before FF shut down on me. Then I realised that the file NPOJI610.dll was not in the plugin folder, so I copied it into the FF plugin folder. Even so, whenever I tried to verify my installation again, FF simply shut down suddenly and when I restart FF, FF will ask me whether I want to restore my previous session.
    I’m so frusturated with this since this is only one of the few problem FF2 has given me. Please help if you can! I’ll be grateful…

  30. Unfortunately your tip does not work for me.
    XP SP2, JRE 1.5.0_11 (newest), and I cannot start applets in Firefox (
    Renaming NPOJI610.dll cannot resolve the problem, as it is not in Firefox’s plugin directory (only Flash plugin is there).
    I tried to copy the whole NP*** dll set from JRE bin directory to the Firefox plugin directory, but this has not effect.

    Any help is highly appreciated!

  31. Glad to see this is still helping!

    The quickest way to get this up the list in the search engines is to link back to the article, so get linking y’all.

  32. This took me a very long time to fix. This problem isn’t very well documented.
    Thank you! Somehow bump this to the top of Google.

  33. Excellent tip, it worked for me as well. I renamed the DLL and now my applets run fine. I had installed a piece of software that installed an old JDK 1.3.1_16, apparently that had added this OLD dll back to the directory.


  34. Thanks for the tip. I was having the same problem getting Firefox to run Java 1.5.0_10 applets. Everyone kept saying that I needed to Enable Java in Firefox (which I had done) and that I needed to Enable Mozilla in JavaConsole->Advanced->AppletTagSupport (which kept saying “Unable to change Browser Settings”). Your tip was spot-on. I renamed “NPOJI610.dll” in “C:\Program Files\Mozilla Firefox\plugins”, and now Java applets run in Firefox! Thanks!

  35. I checked on my control panel and I saw 3 j2SE Runtime environment 5.0 Update 3, 10 and 11 can I delete 3 and 10? it occupies large space on my DRIVE will it effect my programs? Thanks.

  36. I had the same problem. I did like suggested. I erased the NPOJI610.dll file and reinstalled the J2SE runtime Environment 5.0 Update 9, and it worked fine. Thanks a lot.

  37. @ MMouse – thanks for the tip. It would seem there are a number of ways to link between Firefox and JRE can be lost.

    @ pavel – Glad to have been of some help.

  38. Thank you so much for the suggestion. I’ve struggled a lot with java plugin 1.4.2 to be picked up by the firefox. Firefox was picking up an older plugin 1.4.1.

    Copying NPOJI610.dll from java 1.4.2 jre directory into the firefox directory resolved my issue.

    I’m running Firefox 2 under windows 98. Works great!

  39. Hello Shah,

    I believe I may have had the same problem.

    I was using Firefox and Java fine until recently. Suddenly, I lost the ability to connect to a company intranet using Java. No error messages, the process just did not run with Firefox. Everything was working fine with Internet Explorer, but it would not work with Firefox.

    What I realized was that I had recently updated Java with “J2SE runtime Environment 5.0 Update 9”

    I went to control panel, add/remove programs, and I removed update 9. (I used the “change” function, then selected remove. I don’t know if that is any different that choosing the “uninstall”, but I knew I did not want to fully uninstall Java). That fixed the problem for me immediately. I am once again able to connect to the private network with the Java enabled Firefox.


  40. Help me please…
    I just installed Firefox 2.0, and all of a sudden, my username/password isn't being inserted in the signon window (it always was before). I tried the usual suspects–I did not mistakenly tell FF not to remember the password for this site; and I also tried the remember password bookmarklet, but all to no avail–FF will not ask me to remember this password. What do I need to do to get around this?

  41. Hi I am facing a similar Java Error. Only this time the error is not displayed and only the applets never run.
    I am running XP sp2, Firefox 2.0, not sure about Java & Java Script version but I think its the latest.

    can anyone help me on this. i’ll be highly obliged.

  42. I use firefox 1.0.5 and Java JRE 1.5.0_05. After several minutes, the firefox will get restarted and even my pc get restarted. What happens with my firefox anf java?
    Can anyone give me any advice?



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