ERXExtensions have not been initialized.

When your application starts running you might get the message:

ERXExtensions have not been initialized. Please report the classpath and the rest of the bundles to the Wonder mailing list:
Remaining [JavaXML, JavaFoundation, ERJars, JavaEOControl, JavaWOExtensions, JavaEOAccess, JavaJDBCAdaptor, JavaWOSMIL, ERExtensions, JavaWebObjects]

Fix 1

Check your main routine - it should be:

public static void main (String argv []) {
    // Do not put any calls to Wonder code here.
    ERXApplication.main (argv, Application.class);
}

You can have other code in here before the call to ERXApplication, but you can't have calls to any Wonder stuff before the call to ERXApplication.main. This interferes with the order in which Wonder frameworks are loaded, which causes the above problem.