Fixing Win32 Error 0x000006C4 (RPC_S_UNSUPPORTED_TYPE)

The error code 0x000006C4 translates to RPC_S_UNSUPPORTED_TYPE. This error message indicates that the RPC communication encountered an unsupported data type during the call.

Understanding Unsupported Data Types:

• In RPC communication, data is exchanged between client and server. Data can be of various types like integers, strings, or complex structures.
• The RPC_S_UNSUPPORTED_TYPE error occurs when the client attempts to send or receive data of a type that is not supported by the server or the chosen RPC protocol.

Reasons Behind RPC_S_UNSUPPORTED_TYPE:

There are a couple of reasons why you might encounter this error:

• Incompatible Data Type Definitions: The client and server might be using different definitions for the same data type, leading to misunderstandings during data exchange.
• Custom Data Types (less common): If using custom data types in your RPC communication, the server might not be configured to handle them.
• Client-Side Code Issue: The client code might be sending data of a type that is not valid for the remote procedure on the server.

Resolving RPC_S_UNSUPPORTED_TYPE:

1. Review Data Type Definitions:

   • Examine the data type definitions used on both the client and server sides. Ensure they are consistent and compatible for the data being exchanged in the RPC call.

2. Consult Program Documentation:

   • Refer to the documentation for the program or service you’re trying to access remotely. It should specify the data types expected for the remote procedure.

3. Verify Data Marshalling (if applicable):

   • If you have control over data marshalling code, ensure it correctly handles data type conversions between the client and server representations.

4. Simplify Data Types (if possible):

   • Consider simplifying the data types being used in the RPC call, especially if using custom types. Opt for standard or well-supported data types on both sides.

5. Software Vendor Support:

   • If the issue persists, consider contacting the software vendor’s support for the program or service. They might have insights into supported data types or specific requirements for their software.

6. Advanced Debugging (if applicable):

   • In advanced troubleshooting scenarios, tools like network protocol analyzers can be used to capture RPC traffic and examine the contents of data packets. This might reveal the specific data type causing the issue.

Additional Tips:

• Some RPC development libraries or frameworks might offer functionalities to validate data types used in RPC calls.
• When defining custom data types for RPC communication, ensure they are compatible with the chosen RPC protocol and can be correctly marshalled between the client and server.

By understanding the concept of data types in RPC and the reasons behind the RPC_S_UNSUPPORTED_TYPE error, you can identify the cause of the incompatibility. Reviewing data type definitions, consulting program documentation, verifying data marshalling (if applicable), simplifying data types (if possible), contacting software vendor support, using advanced debugging (if applicable), and utilizing RPC development tools for validation can help address this error.