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Java Troubleshooting

load: class XXXX not found

or ...

applet appears as a (dead) grey rectangle


When attempting to run an applet within Microsoft Internet Explorer the applet appears as a grey rectangle, with no activity and the applet is most definitely not running.

Moving the cursor over the grey applet area may reveal the message:

load: class XXXX not found

where 'XXXX' is the name of the applet.

Possible Causes and Remedies:

  • Developers only: The most likely cause is that the class name is misspelt. This is unlikely to be the problem for pages viewed over the web, where it can normally be assumed that the webmaster would have resolved such issues. If the name is misspelt (or the class is genuinely not available) then only the developer can resolve this.
    • Check the spelling of the class name, ensure that the compiled applet is available and that its name ties up with that specified in the html file.
  • There may be a mismatch between the version of the Java SDK that the applet was created with and the version of the Java RE (run-time environment) locally environment installed. This is only an issue if the applet was created with a later version of the Java SDK than the local Java RE. Note: This only seems to be a problem with Internet Explorer.
  • Developers only: (Tip contributed by Mark Lowton, from

    Try recompiling the code using the following:

    Javac -target 1.1

    Where 1.1 is the release of the Java VM you wish the .class file to work on.

These notes are believed to be correct for Java 1.4.1 with Internet Explorer 6 and may apply to other versions as well.

About the author: is a dedicated software developer and webmaster. For his day job he develops websites and desktop applications as well as providing IT services. He moonlights as a technical author and consultant.