What does Windows error code 1915 (RPC_S_INVALID_ASYNC_CALL) mean?

RPC_S_INVALID_ASYNC_CALL

The requested action conflicts with the async call lifecycle

RPC_S_INVALID_ASYNC_CALL differs from an invalid handle: the state object can be recognized, but the associated call is not valid for the requested operation. Examples include completing twice, querying or canceling after final completion, using a client-side operation on server state, or acting before the asynchronous call has been issued successfully.

Model the lifecycle explicitly: initialize, issue, wait or query, optionally cancel, and perform exactly one final completion path. Record every transition atomically when multiple threads can observe the call. Do not infer that a notification alone authorizes completion; obtain current status and follow the documented API contract.

What to inspect

• Maintain a single owner for terminal completion of each async call.
• Reject duplicate cancel, abort, or complete operations in application code.
• Correlate notifications with the exact RPC_ASYNC_STATE instance.

References

• Microsoft: client-side asynchronous RPC lifecycle
• Microsoft: querying asynchronous call state
• Microsoft: final completion rules