The error code 0x000006B4 translates to RPC_S_UNKNOWN_MGR_TYPE. This error message indicates an issue with the manager type specified in the binding string used for a Remote Procedure Call (RPC) connection.

Understanding Manager Types in RPC:

• In RPC communication, the binding string defines various details about the connection, including the manager type.
• The manager type specifies the underlying RPC protocol or transport mechanism used to establish the connection.
• Common manager types include ncacn_np (named pipes), ncacn_ip_tcp (TCP/IP), and others depending on the specific RPC implementation.

Reasons Behind RPC_S_UNKNOWN_MGR_TYPE:

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

• Incorrect Manager Type Specified: The binding string might be using an incorrect or unsupported manager type. This could be due to typos, outdated syntax, or a manager type not available on the target system.
• Incompatible RPC Implementations: In rare cases, a mismatch between the RPC implementation on the client and server might lead to unrecognized manager types.

Resolving RPC_S_UNKNOWN_MGR_TYPE:

1. Verify Binding String Manager Type:

   • Carefully examine the manager type specified within the binding string. Ensure it’s a valid and supported manager type on both the client and server machines.

2. Consult Program Documentation:

   • Refer to the documentation for the program or service you’re trying to access remotely. It should specify the required or recommended manager type for the RPC connection.

3. Software Vendor Support:

   • If you’re unsure about the appropriate manager type or encounter issues related to RPC implementation compatibility, consider reaching out to the software vendor’s support for the program or service you’re trying to access remotely. They can provide guidance on compatible manager types and potential compatibility issues.

4. Review Available Manager Types (if applicable):

   • If you have access to server administration tools or RPC configuration options, check the available manager types supported on the server. This can help you choose a compatible option for the binding string.

5. Explore Alternative Manager Types (if possible):

   • In some cases, the program or service you’re using might allow specifying alternative manager types in the binding string. Explore the documentation or configuration options to see if there are compatible alternatives you can try.

Additional Tips:

• Some RPC tools or libraries might offer features to help with selecting the appropriate manager type during connection setup. These tools might suggest compatible manager types based on system capabilities.
• If managing the client or server configuration, ensure both systems are using compatible RPC implementations and that the chosen manager type is supported by both sides.

By understanding the role of manager types in RPC and the reasons behind the RPC_S_UNKNOWN_MGR_TYPE error, you can identify the cause of the unrecognized manager type. Carefully verifying the binding string manager type, consulting program documentation, contacting software vendor support, reviewing available manager types (if applicable), exploring alternative manager types (if possible), and ensuring compatible RPC implementations can help address this error.