To reproduce this use the cxf/noemax interop test in jbossws/projects (uncomment echoStruct() call in NoemaxClient).

javax.xml.ws.soap.SOAPFaultException: Unmarshalling Error: null
at org.apache.cxf.jaxws.JaxWsClientProxy.invoke(JaxWsClientProxy.java:145)
at $Proxy41.echoStruct(Unknown Source)
at org.jboss.test.ws.fastinfoset.NoemaxClient.echoStruct(NoemaxClient.java:124)
at org.jboss.test.ws.fastinfoset.NoemaxClient.run(NoemaxClient.java:96)
at org.jboss.test.ws.fastinfoset.NoemaxClient.main(NoemaxClient.java:182)
Caused by: org.apache.cxf.interceptor.Fault: Unmarshalling Error: null
at org.apache.cxf.jaxb.JAXBEncoderDecoder.unmarshall(JAXBEncoderDecoder.java:629)
at org.apache.cxf.jaxb.JAXBEncoderDecoder.unmarshall(JAXBEncoderDecoder.java:527)
at org.apache.cxf.jaxb.io.DataReaderImpl.read(DataReaderImpl.java:108)
at org.apache.cxf.interceptor.DocLiteralInInterceptor.handleMessage(DocLiteralInInterceptor.java:102)
at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:236)
at org.apache.cxf.endpoint.ClientImpl.onMessage(ClientImpl.java:641)
at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.handleResponseInternal(HTTPConduit.java:2108)
at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.handleResponse(HTTPConduit.java:1987)
at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.close(HTTPConduit.java:1912)
at org.apache.cxf.transport.AbstractConduit.close(AbstractConduit.java:66)
at org.apache.cxf.transport.http.HTTPConduit.close(HTTPConduit.java:611)
at org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor.handleMessage(MessageSenderInterceptor.java:62)
at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:236)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:469)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:299)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:251)
at org.apache.cxf.frontend.ClientProxy.invokeSync(ClientProxy.java:73)
at org.apache.cxf.jaxws.JaxWsClientProxy.invoke(JaxWsClientProxy.java:124)
... 4 more
Caused by: java.lang.NullPointerException
at com.sun.xml.bind.DatatypeConverterImpl._parseBoolean(DatatypeConverterImpl.java:258)
at com.sun.xml.bind.v2.runtime.unmarshaller.XsiNilLoader.selectLoader(XsiNilLoader.java:66)
at com.sun.xml.bind.v2.runtime.unmarshaller.ProxyLoader.startElement(ProxyLoader.java:53)
at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$IntercepterLoader.startElement(ElementBeanInfoImpl.java:231)
at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext._startElement(UnmarshallingContext.java:455)
at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext.startElement(UnmarshallingContext.java:433)
at com.sun.xml.bind.v2.runtime.unmarshaller.InterningXmlVisitor.startElement(InterningXmlVisitor.java:71)
at com.sun.xml.bind.v2.runtime.unmarshaller.StAXStreamConnector.handleStartElement(StAXStreamConnector.java:275)
at com.sun.xml.bind.v2.runtime.unmarshaller.StAXStreamConnector.bridge(StAXStreamConnector.java:209)
at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:360)
at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:339)
at org.apache.cxf.jaxb.JAXBEncoderDecoder.unmarshall(JAXBEncoderDecoder.java:607)
... 21 more