From: <glassfish_at_javadesktop.org>
Date: Sun, 03 Jun 2007 08:14:14 PDT

I just had the same problem...

This exception comes when the server and the client don't use the same JVM (my case : 1.5 on client and 1.6 on server) they don't calculate the same id for the same class ...
I solved this issue by handling the id in the code :
You just need to add
private static final long serialVersionUID = 1L;
in each entity class

Every time you add or remove a non transient field, you need to increment the id...
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