What does NTSTATUS 0xC00000AF (STATUS_ILLEGAL_FUNCTION) mean?

STATUS_ILLEGAL_FUNCTION

The named-pipe operation was issued on the wrong pipe end

Record the operation issued to the pipe handle and its current mode and state. A handle can be valid while a particular control or I/O function is not supported for that pipe endpoint.

Some pipe operations are valid only on the server end. This status points to a wrong-handle problem rather than malformed data in the pipe message.

What to inspect

• Confirm whether the handle came from CreateNamedPipe or CreateFile.
• Do not call server-only operations on the client end.
• Log handle ownership when a pipe handle is passed between threads or processes.

References for STATUS_ILLEGAL_FUNCTION

• Microsoft Open Specifications: NTSTATUS values
• Microsoft: Named Pipes
• Microsoft: Named Pipe Type, Read, and Wait Modes
• Microsoft: Named Pipe Operations