Fixing Win32 Error 0x000006D0 (RPC_S_PROTSEQ_NOT_FOUND)

The error code 0x000006D0 translates to RPC_S_PROTSEQ_NOT_FOUND. This error message indicates that the RPC call failed because the specified protocol sequence (ProtSeq) is not supported or not found on the server.

Understanding Protocol Sequences in RPC:

• In RPC communication, protocol sequences (ProtSeqs) define the specific communication protocols used to transmit data between client and server. Common ProtSeqs include ncacn_ip_tcp (TCP over IP) and ncacn_np (named pipes).
• Clients specify the desired ProtSeq when making an RPC call.
• The RPC_S_PROTSEQ_NOT_FOUND error occurs when the client attempts to use a ProtSeq that is not supported by the server or is not configured for the service being accessed.

Reasons Behind RPC_S_PROTSEQ_NOT_FOUND:

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

• Incorrect Client Configuration: The client application might be configured to use a ProtSeq that is not supported by the server.
• Disabled ProtSeq on Server: The desired ProtSeq might be disabled on the server, even though it’s technically supported.
• Outdated Client Software (less common): In rare cases, if using outdated client software, it might be programmed to use an older or less common ProtSeq that is no longer supported by the server.

Resolving RPC_S_PROTSEQ_NOT_FOUND:

1. Verify Client Configuration:

   • Examine the client application’s configuration settings related to RPC communication. Ensure it’s set to use a ProtSeq that is known to be supported by the server.

2. Consult Program Documentation:

   • Refer to the documentation for the program or service you’re trying to access remotely. It should specify the supported ProtSeqs for RPC calls.

3. Server Administrator Communication (if possible):

   • If possible, communicate with the server administrator to determine the available ProtSeqs on the server. This can help you adjust the client configuration accordingly.

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 compatible ProtSeqs or troubleshooting steps for their software.

5. Server Configuration Adjustment (advanced):

   • In some scenarios (with server administrative access), you might be able to enable the desired ProtSeq on the server if it’s disabled. However, enabling unsupported ProtSeqs can introduce security risks, so proceed with caution.

Additional Tips:

• Some RPC development tools or libraries might offer functionalities to specify the ProtSeq used for RPC calls.
• Debuggers or logging mechanisms can help capture details about the ProtSeq being used in the client code and any error messages related to unsupported ProtSeqs.

By understanding the role of ProtSeqs in RPC and the reasons behind ProtSeq not found errors, you can identify the cause of the incompatibility. Verifying client configuration, consulting program documentation, communicating with the server administrator (if possible), contacting software vendor support, and adjusting server configuration (advanced) can help address this error. Remember to prioritize using supported ProtSeqs and avoid enabling unsupported ones on the server unless absolutely necessary.