Fixing Win32 Error 0x000006D6 (RPC_S_UNKNOWN_AUTHZ_SERVICE)

The error code 0x000006D6 translates to RPC_S_UNKNOWN_AUTHZ_SERVICE. This error message indicates that the RPC call failed because the client attempted to use an authorization service that the server does not recognize or support.

Understanding Authorization Services in RPC:

In addition to authentication (verifying user identity), RPC communication might involve authorization (verifying user permissions). While authentication mechanisms determine who you are, authorization mechanisms determine what you can do.

• Authorization Services: Some RPC security configurations might involve a separate authorization service to determine user permissions for accessing specific RPC functionalities.
• Error Scenario: The RPC_S_UNKNOWN_AUTHZ_SERVICE error occurs when the client tries to use an authorization service that is not configured or supported on the server.

Reasons Behind RPC_S_UNKNOWN_AUTHZ_SERVICE:

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

• Misconfigured Client: The client application might be configured to use an authorization service that is not compatible with the server’s setup.
• Outdated Client Software (less common): In rare cases, if using outdated client software, it might be programmed to use an older authorization service no longer supported by the server.
• Server-Side Configuration (less common): The server might not be configured to use any authorization service at all, while the client is expecting one.

Resolving RPC_S_UNKNOWN_AUTHZ_SERVICE:

1. Verify Client Configuration:

   • Examine the client application’s configuration settings related to RPC security. Ensure it’s not attempting to use an authorization service unless the server actually supports it.

2. Consult Program Documentation:

   • Refer to the documentation for the program or service you’re trying to access remotely. It should clarify if authorization services are involved in RPC communication and if specific ones are supported.

3. Server Administrator Communication (if possible):

   • If possible, communicate with the server administrator to determine if authorization services are used for the RPC functionality you’re trying to access.

4. Software Vendor Support:

   • If the issue persists, consider contacting the software vendor’s support for the program or service. They might have insights into authorization requirements or troubleshooting steps for their software.

5. Adjust Client Configuration (if applicable):

   • If the server doesn’t use authorization services, adjust the client configuration to remove any settings related to authorization services.

Additional Tips:

• Some RPC development tools or libraries might offer functionalities to configure security settings for RPC calls, including authorization.
• Debuggers or logging mechanisms can help capture details about the attempted authorization service and any error messages related to unsupported services.

By understanding the role of authorization services in RPC and the reasons behind unknown authorization service errors, you can identify the incompatibility. Verifying client configuration, consulting program documentation, communicating with the server administrator (if possible), contacting software vendor support, and adjusting client configuration (if applicable) can help address this error. It’s important to configure the client based on the server’s actual security setup.