Java Applet Troubleshooting Guide

The VoxForge Speech Submission Application requires the following:

  1. Java version 1.5 or greater;
  2. Java enabled in your browser;
  3. If you are using a Linux that has an open source Java that does not support signed applets (e.g. OpenJDK or IceTea), then you need Sun's JRE (Java Runtime Environment);
  4. Special Java configurations if running behind a proxy server (see below for instructions); and
  5. Special setup for Linux USB microphones (see below).

How to determine if Java is installed on your PC

If Java is working properly on your browser you will see a grey rectangle below this paragraph with one line of text that says something like "Java Version 1.5.0_12 from Sun Microsystems Inc.":


symptom: you see text stating something like: "Browser has Java disabled"

problem: the Java Run-time Environment ("JRE") is installed on your computer, but it is disabled in your web browse, or you don't have a java plugin installed in your browser


1. To enable Java in your browser, click one of these links:

2. To install a java plugin in your browser

You might also need to Clear your Web Browser Cache to get Java to work in your browser.

symptom: you see the outline of a white box with no text in it

problem: Java is not Installed on your compute




symptom: you see a grey box with no text in it

Problem: Older version of Java.

Solution: Go to Sun's Verify your Java Installation and follow the instructions on the page to upgrade the version of Java on your computer.

Other Problems

symptom: can't see the waveform display on Java applet

Problem: Zoom settings in browser window are incorrectly set.

Solution: FireFox: View > Zoom: click "Zoom in" until waveform display is visible (can also use your mouse wheel to change zoom settings).

Other Resources


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By kmaclean - 2/2/2016

Firefox works with VoxForge Java applet on Linux

Ubuntu & Linux Java

(see: How To Install Java on Ubuntu with Apt-Get)

install OpenJDK (Java on Ubuntu) and Icedtea (browser plugin)

$ sudo apt-get install default-jre

$ sudo apt-get install icedtea-7-plugin

restart firefox

Fedora & Linux Java

(see: Java FAQ)

install OpenJDK (Java on Fedora) and Icedtea (browser plugin)

$ su -c "dnf install java-1.?.0-openjdk"

$ su -c "dnf install icedtea-web"

restart firefox

Fedora and Oracle Java

You need to follow the instructions on this page: Use the Java plugin to view interactive content on websites, which then point you to Oracle's Manual Installation and Registration of Java Plugin for Linux article for help installing or updating Java on your Linux system.

Basically, you need to install Oracle version of Java.  Then create a link to the Java plugin file is included as part of that install in Mozill'a plugin directory, as follows:

1. go to firefox plugin directory:

$ cd ~/.mozilla/plugins

2. create link to the Java browser plugin:

for Intel-based computers:

$ ln -s /usr/java/latest/jre/lib/i386/ .

or for AMD-based computers:

$ ln -s /usr/java/latest/jre/lib/amd64/ .

3. restart firefox


By kmaclean - 5/6/2015

The Java plug-in for web browsers used by the VoxForge applet relies on the NPAPI (Netscape Plug-in API) cross platform plugin architecture.

Starting with Windows Chrome Version 42, Google has added an additional step to configuring NPAPI based plugins like Java to run

  1. In your URL bar, enter:
  2. Click the Enable link for the Enable NPAPI configuration option.
  3. Click the Relaunch button that now appears at the bottom of the configuration page.

(Note: Chrome NPAPI support was removed from the Linux platform starting with Chrome version 35)

You can still use:  Firefox, Internet Explorer or Safari.


Update - Sept 15, 2015, from Google website:

Plugin-based content doesn't work on Chrome

To make browsing with Chrome safer, faster, and more stable, we stopped allowing NPAPI plugins on September 1, 2015.

Plugins that use NPAPI, including Silverlight, Java, and Unity, won’t work.

By kmaclean - 9/27/2014

from the Oracle Java faq:

Chrome and Linux

Starting with Chrome version 35, NPAPI (Netscape Plug-in API) support was removed for the Linux platform. For more information, see Chrome and NPAPI (

Firefox is the recommended browser for Java on Linux.

From Slav' post: What does the removal of NPAPI plugin support mean to an end user?

  • Java will have to re-write their plugin for Chrome to use new API



By kmaclean - 1/14/2016

If your browser is behind a proxy server, please set up your Java JRE as follows: 

  • Open the JRE control panel:
    • Windows: located in system control panel under Java (Start>Control Panel>Java - If this isn't visible, ensure you're using "Classic View", and not "Category View");
    • Linux: located in System>Preferences>Java (or execute jcontrol from the command line);
  • Click the "General" tab, then click the "Network Settings..." button. Enter  proxy settings as directed by your local system administrator;
  • Restart your web browser

By priya - 1/28/2015 - 750 Replies

can julius be interfaced with visual studio?

By kmaclean - 6/14/2010 - 389 Replies

The speechsubmission applet does not seem to work with newer versions of the OpenJDK (see this bug report [Bug 540962] [abrt] crash detected in java-1.6.0-openjdk-1: ).

As a workaround, you will need to install Sun's Java:

By Jeevesbond - 8/22/2010 - 242 Replies

The Java applet generated a security error for me: 'access denied (javax.sound.sampled.AudioPermission record)'.

Unfortunately I lacked more than five minutes to try and fix the issue, so gave up trying.

By kmaclean - 5/8/2010

The message: "Browser has Java disabled" may be the result of Java and your browser plugin not being installed:

  • Ubuntu install:
    • OpenJDK Java 6 Runtime
    • icedTea Java Plugin
  • Fedora
    • OpenJDK Runtime Environment (1.6.0)
    • OpenJDK Web Browser Plugin

By mdeisher - 10/6/2008 - 10 Replies

The java applet seems to behave just fine (recording and playback work) but when I upload the result, the "Uploading..." message is displayed and it never completes.  I waited about 20 minutes.  Suggest that you add a progress meter or some way to confirm that the upload is happening.  Also suggest you add the capability to save the zip file locally so that the recordings are not lost and can be sent it manually.

By Robert (Jamie) Munro - 4/30/2008 - 6 Replies

I'm getting the error:
ERROR Line matching interface TargetDataLine supporting format PCM_SIGNED, 48000.0 Hz, 16 bit, mono, little-endian not supported.
in the area where the waveform should appear, on "Java Version: 1.5.0_13 from Apple Computer, Inc."

This is almost the same error as this trac ticket:

I can't see how to get a trac login and reopen that ticket.

By Sergey - 4/29/2008 - 19 Replies

I have got a studio quality USB microphone "Snowball" but when I try to record my voice using the applet it records silence. I tested the microphone in Audacity - it works (though I need to adjust the sample rate) and my java seems to be good: java version "1.6.0_03".

What might be wrong?


P.S. I am using Russian version of the aplet

and my computer is Ubuntu 7.10, kernel, GNOME 2.20.1, Memory 2GB, CPU AMD X2 Dual Core BE-2400 

Thanks a lot,



By V - 3/16/2008 - 4 Replies


According to every java testing site I have Java 1.7 properly installed, still I see only an empty grey box  on the Troubleshooting page. (And can't find the applet in general.)