Applet not found by IE6 under XP (ClassDefNotFound)

[Jim]

I have a peculiar case where an applet failes to load - Internet Explorer
6.0 can't seem to find my applet when it's run under XP
I've wandered around the newsgroups and Microsoft's support site but found
nothing definitive.

Has anyone else seen this problem? I really need a solution as I need to
deploy this web site soon in an environment where
may machine are being upgraded to XP

Here's some more facts:
IE6/XP combination fails on multiple machines.
IE6 can find the applet can under win2k
Netscape works fine
If turn on Java logging in the internet options, the log shows a
ClassDefNotFound error whenever a page with the applet is loaded.
On a Java development machine, IE6/XP works find BUT if (in IE6) I go to
tools/internet options/advanced and UNcheck the
'use Java 2 v1.41...' options, the applet fails to load.
Disabling the JIT compiler makes no difference.
I can't see anything obvious in the security settings (but I'm pretty
ignorant here)
Have not tried earlier IE versions.
SP1 is installed for IE6 (version: 6.0.2800.1106.xpsp1.020828-1920; Update
Versions: SP1;Q819847;Q813951)

I did find one item on Microsoft's site (knowledge base article 177754) that
said the Microsoft virtual machine
would some times exhibit this behavior in version 4.79.2252 but was fixed in
version 4.79.2334 and later. However, this
article is said to apply to IE4.0

I could not find a way to down load a late version of the VM. All I could
find was information on how to 'transition away'
from the Microsoft VM.

Is there a way for a web page to query the browser about what VM it's using?
Is there a 'classpath' of any sort the browser uses or is it all up the the
webserver (which is Tomcat)?

I sure would appreciate any advice or pointers.

 

[Ike]

Take a look at :

http://www.technalink.com/vdist/common/trouble1.htm

Also, go into the XP Control panel, open java plugin - browswers tab - make
sure MS IE is checked -Ike

 

[Andrew Thompson]

....
| On a Java development machine, IE6/XP works find BUT if (in
IE6) I go to
| tools/internet options/advanced and UNcheck the
| 'use Java 2 v1.41...' options, the applet fails to load.

You've given us a great deal of information
Jim, but missed two _very_ imortant things.
1) The _source_
2) An URL

I am almost certain I know what the trouble
is, but I am not wading through your post
trying to guess.. Provide the two things above
and I'l have a look.

[ BTW - Sounds like a JVM version problem ->
http://www.physci.org/test/JRE/ ]

 

[martinwells]

There's a much simpler reason for seeing this.

The MSJVM byte code format is old so it's unable to read the updated versions being produced by modern JavaC versions. Since the JVM is unable to load the class (it thinks it's corrupt) it gives the rather misleading ClassDefNotFound exception.

Recompile your classes using the 1.1 byte code format and it'll work fine (javac has an option for this).

 

[Andrew Thompson]

There's a much simpler reason for seeing this.

What? My news reader has dropped the
thread, so it might be nice to provide a
context for your comment.

The MSJVM byte code format is old so it's unable to read the updated
versions being produced by modern JavaC versions. Since the JVM is
unable to load the class (it thinks it's corrupt) it gives the rather
misleading ClassDefNotFound exception.

Recompile your classes using the 1.1 byte code format and it'll work
fine (javac has an option for this).

It will not do you any good unless
you exclude all classes that are
post 1.1.

Either that or the obsolete, decrepit,
broken, security flawed MS 1.1 VM
will still not run the applet.

Replace that piece of junk with a modern
Sun Java Plug-In and be done with it.