Hello! I have similar problems, while instrumenting classes I get various exceptions: Caused by: java.lang.NullPointerException | at javassist.bytecode.ConstPool.getInterfaceMethodrefClassName(ConstPool.java:413) | at javassist.expr.MethodCall.getClassName(MethodCall.java:91) | at javassist.expr.MethodCall.getCtClass(MethodCall.java:75) | at javassist.expr.MethodCall.getMethod(MethodCall.java:114) And: Caused by: java.lang.ClassCastException: javassist.bytecode.ClassInfo | at javassist.bytecode.ConstPool.getFieldrefClassName(ConstPool.java:254) | at javassist.expr.FieldAccess.getClassName(FieldAccess.java:97) | at javassist.expr.FieldAccess.getCtClass(FieldAccess.java:89) | at javassist.expr.FieldAccess.getField(FieldAccess.java:112) Any idea what causes these failures? Regards Martin View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4130760#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...