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A fix for Java applets not loading in Firefox

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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