Fixing Win32 Error 0x000006DC (RPC_S_INVALID_VERS_OPTION)

The error code 0x000006DC translates to RPC_S_INVALID_VERS_OPTION. This error message indicates that the RPC call failed because the client specified an invalid version option.

Understanding Versioning in RPC:

• In RPC (Remote Procedure Calls), both servers and interfaces (the functionalities offered by servers) can have versions.
• Versioning allows for evolving functionalities while maintaining compatibility with older clients.
• Clients typically specify a version option when making RPC calls, indicating which version of the interface they expect to use.
• The RPC_S_INVALID_VERS_OPTION error occurs when the client specifies a version option that is not supported by the server or the interface being accessed.

Reasons Behind RPC_S_INVALID_VERS_OPTION:

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

• Incorrect Version Specified: The client code might be programmed to use an outdated or incompatible version number for the interface.
• Missing Version Information: In some cases, the client might not be specifying a version option at all, which could be an issue if the server requires it.
• Server-Side Version Changes (less common): If the server administrator recently upgraded the server-side interface to a new version, the client might be unaware of the change and still attempt to use an older version.

Resolving RPC_S_INVALID_VERS_OPTION:

1. Review Client-Side Code:

   • Examine the part of your client code responsible for making the RPC call. Verify that it specifies the correct version option for the interface being accessed.

2. Consult Program Documentation:

   • Refer to the documentation for the program or service you’re trying to access remotely. It should specify the supported versions of the interface and how to indicate the desired version in RPC calls.

3. Update Client Software (if applicable):

   • Consider updating the client software to the latest version. This might ensure it uses the compatible version information for the interface.

4. Server Administrator Communication (if possible):

   • If possible, communicate with the server administrator to determine the supported versions of the interface and any specific version requirements for RPC calls.

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 compatible version options or troubleshooting steps for their software.

Additional Tips:

• Some RPC development tools or libraries might offer functionalities to specify or validate version options in RPC calls.
• Debuggers or logging mechanisms can help capture details about the version option used in the RPC call and any error messages related to invalid versions.

By understanding the concept of versioning in RPC and the reasons behind invalid version option errors, you can identify the cause of the incompatibility. Reviewing client-side code, consulting program documentation, updating client software (if applicable), communicating with the server administrator (if possible), contacting software vendor support, and utilizing RPC development tools (if applicable) can help address this error.