When unmarshalling an Exception, a NPE is thrown on the reading side:

java.lang.NullPointerException
at org.jboss.marshalling.river.RiverUnmarshaller.doInitSerializable(RiverUnmarshaller.java:1437)
at org.jboss.marshalling.river.RiverUnmarshaller.doInitSerializable(RiverUnmarshaller.java:1395)
at org.jboss.marshalling.river.RiverUnmarshaller.doInitSerializable(RiverUnmarshaller.java:1395)
at org.jboss.marshalling.river.RiverUnmarshaller.doInitSerializable(RiverUnmarshaller.java:1395)
at org.jboss.marshalling.river.RiverUnmarshaller.doInitSerializable(RiverUnmarshaller.java:1395)
at org.jboss.marshalling.river.RiverUnmarshaller.doReadNewObject(RiverUnmarshaller.java:1083)
at org.jboss.marshalling.river.RiverUnmarshaller.doReadObject(RiverUnmarshaller.java:221)
at org.jboss.marshalling.river.RiverUnmarshaller.doReadObject(RiverUnmarshaller.java:158)
at org.jboss.marshalling.AbstractUnmarshaller.readObject(AbstractUnmarshaller.java:81)
at org.infinispan.marshall.jboss.externalizers.ExceptionResponseExternalizer.readObject(ExceptionResponseExternalizer.java:27)
at org.infinispan.marshall.jboss.ConstantObjectTable$DelegatingReadWriter.readObject(ConstantObjectTable.java:258)
at org.infinispan.marshall.jboss.ConstantObjectTable.readObject(ConstantObjectTable.java:224)
at org.jboss.marshalling.river.RiverUnmarshaller.doReadObject(RiverUnmarshaller.java:304)
at org.jboss.marshalling.river.RiverUnmarshaller.doReadObject(RiverUnmarshaller.java:158)
at org.jboss.marshalling.AbstractUnmarshaller.readObject(AbstractUnmarshaller.java:81)
at org.infinispan.marshall.jboss.JBossMarshaller.objectFromObjectStream(JBossMarshaller.java:203)
at org.infinispan.marshall.VersionAwareMarshaller.objectFromByteBuffer(VersionAwareMarshaller.java:91)
at org.infinispan.marshall.VersionAwareMarshaller.objectFromByteBuffer(VersionAwareMarshaller.java:164)
at org.infinispan.marshall.jboss.JBossMarshallerTest.testExceptionResponse(JBossMarshallerTest.java:328)