The bug has been originally reported against the NetBeans IDE running on J2SE 1.5-beta b32c and 1.5-beta2 b40:
http://www.netbeans.org/issues/show_bug.cgi?id=40568

'Stepping Into' in the NetBeans debugger sometimes causes the 'Unexpected JDWP Error: 35' exception to be thrown. It turns out that it happens when the Netbeans JPDA debugger tries to evaluate 'this' object reference in the current stack frame. As a result, instance variables values cannot be inspected during debugging. It seems to be reliably reproducible with some test cases on some configurations only.

The exception stack trace starts with:

com.sun.jdi.InternalException: Unexpected JDWP
Error: 35
        at
com.sun.tools.jdi.JDWPException.toJDIException(JDWPException.java:47)
        at
com.sun.tools.jdi.StackFrameImpl.thisObject(StackFrameImpl.java:126)
        at
org.netbeans.modules.debugger.jpda.JPDACallStackFrame.getVariables(JPDACallStackFrame.java:220)

Steps to reproduce with NetBeans dev build (#200402261900):

1. Open the attached class source in the editor.
2. Place a breakpoint at line 35 -- 'Set s = ...'
3. Start the debugger via Alt-F5
4. After it stops at the breakpoint, start pressing F7 (confirm 'Step Out' / 'Don't Ask')
5. The first stack trace appears when the Name class constructor is stepped into for the first time. A series of stack traces is generated with each F7 after that.

I was not able to reproduce the behavior with JDK
1.4.2_03.

A test case and a full exception stack trace are attached.
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