Fixing Win32 Error 0x000006CE (RPC_S_MAX_CALLS_TOO_SMALL)

The error code 0x000006CE translates to RPC_S_MAX_CALLS_TOO_SMALL. This error message indicates that the RPC call failed because the client attempted to use a concurrency level that the server is not configured to support.

Understanding RPC Concurrency:

• In RPC communication, concurrency refers to the ability to handle multiple simultaneous RPC calls on the server.
• The server administrator can configure a maximum concurrency level, which specifies the number of concurrent RPC calls it can handle efficiently.
• The RPC_S_MAX_CALLS_TOO_SMALL error occurs when the client specifies a concurrency level in the RPC call that exceeds the server’s configured maximum.

Reasons Behind RPC_S_MAX_CALLS_TOO_SMALL:

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

• Misconfigured Client: The client application might be configured to use a concurrency level that is higher than what the server can support.
• Server-Side Configuration (less common): In rare cases, the server administrator might have intentionally set a very low maximum concurrency level, and any client attempting a higher level would encounter this error.

Resolving RPC_S_MAX_CALLS_TOO_SMALL:

1. Review Client Configuration:

   • Examine the client application’s configuration settings related to RPC concurrency. Ensure it’s set to a value less than or equal to the server’s maximum supported concurrency level.

2. Consult Program Documentation:

   • Refer to the documentation for the program or service you’re trying to access remotely. It might specify recommendations or limitations regarding RPC concurrency.

3. Server Administrator Communication (if possible):

   • If possible, communicate with the server administrator to determine the server’s configured maximum concurrency level. 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 recommended concurrency settings or troubleshooting steps for their software.

5. Server Configuration Adjustment (advanced):

   • In some scenarios (with server administrative access), you might be able to adjust the server’s maximum concurrency level to accommodate the client’s needs. However, this should be done with caution, considering server performance and resource limitations.

Additional Tips:

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

By understanding the concept of RPC concurrency and how it can lead to errors, you can identify the cause of the maximum calls being too small issue. Reviewing 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. It’s important to prioritize adjusting client-side settings to match server capabilities unless there’s a strong reason to modify the server configuration.