Access Violation in RPCRT4.DLL When Pickling Buffered RPC Data

Pickling, or serialization, is a Remote Procedure Call (RPC) process of marshaling data (encoding) and unmarshaling data (decoding) from buffers that you own. When you pickle and use wire_marshal, you may experience an Access Violation in Rpcrt4.dll. The wire_marshal attribute specifies a data type that will be used for transmission (the wire-type) instead of an application-specific data type (the userm-type). Each userm-type has a one- to-one correspondence with a wire-type that defines the wire representation of the type. You must supply routines to size the data for marshaling, to marshal and unmarshal the data, and to free memory.

NOTE: If there are embedded types in your data that are also defined with wire_marshal or user_marshal, you need to manage the servicing of those embedded types as well.

An uninitialized (NULL) buffer pointer is dereferenced to see if the underlying buffer was overwritten, causing an Access Violation.

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.