The transaction propagation context structure has a references to coordiator and terminator objects, which gets marshalled out as part of the tx svc ctxt.

Inside the interceptor (send_request) point, a singleton ORB is used to create an 'any' to hold the svc ctxt and codec.encode_value(..) is used to encode it into an byte[].

When codec.encode_value tries to copy the any contents into its cdrOut stream, it does a read_Object(..) which fails.

The reason is because the implementation of the cdr.read_Object() uses orb.getSubcontractRegistry() to get the subcontract. But in the case of singleton orbs, there is no subcontract registry, and hence there is no way to do read_Object.