What does Windows error code 1746 (RPC_S_BINDING_HAS_NO_AUTH) mean?

RPC_S_BINDING_HAS_NO_AUTH

RPC_S_BINDING_HAS_NO_AUTH means that the RPC binding handle has no authentication information. A client is not required to configure authentication for every binding, but an operation that requires it cannot use an unauthenticated binding.

Inspect the binding with RPC inquiry APIs or the client configuration and confirm which authentication service, level, and identity the server operation requires. Attach authentication to the binding before the protected call rather than assuming transport connectivity implies RPC security.

What to check

• Call RpcBindingSetAuthInfo on the binding before invoking a procedure that requires authenticated RPC.
• Confirm the server accepts the selected authentication service and level.
• Do not treat transport reachability as authentication; a successful connection can still be rejected because the binding has no credentials.

Microsoft: RpcBindingSetAuthInfo · RPC Return Values