When using a ComplexType containing an element that is an union whose one element is also an union, SourceGenerator falls on a NullPointerException while creating classes. This happens with the latest version that is 0.9.7 and with older ones also. The xsd that shows this problem is given in an attached file. Here is the exception I get : – using UNIX style line separation. – Suppressing non fatal warnings. Creating classes for: CreditCard java.lang.NullPointerException at org.exolab.castor.builder.TypeConversion.compare(TypeConversion.java:567) at org.exolab.castor.builder.TypeConversion.findCommonType(TypeConversion.java:551) at org.exolab.castor.builder.TypeConversion.convertType(TypeConversion.java:132) at org.exolab.castor.builder.binding.XMLBindingComponent.getJavaType(XMLBindingComponent.java:1185) at org.exolab.castor.builder.MemberFactory.createFieldInfo(MemberFactory.java:291) at org.exolab.castor.builder.SourceFactory.processContentModel(SourceFactory.java:1508) at org.exolab.castor.builder.SourceFactory.processContentModel(SourceFactory.java:1552) at org.exolab.castor.builder.SourceFactory.processComplexType(SourceFactory.java:1464) at org.exolab.castor.builder.SourceFactory.createSourceCode(SourceFactory.java:402) at org.exolab.castor.builder.SourceGenerator.createClasses(SourceGenerator.java:1045) at org.exolab.castor.builder.SourceGenerator.createClasses(SourceGenerator.java:931) at org.exolab.castor.builder.SourceGenerator.generateSource(SourceGenerator.java:370) at org.exolab.castor.builder.SourceGenerator.generateSource(SourceGenerator.java:452) at org.exolab.castor.builder.SourceGenerator.generateSource(SourceGenerator.java:485) at org.exolab.castor.builder.SourceGenerator.main(SourceGenerator.java:865)