What does macOS kernel return 0x1000400B (MACH_RCV_HEADER_ERROR) mean?

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: A received message could not transfer one or more header port rights.

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MACH_RCV_IN_SET	MACH_RCV_BODY_ERROR

MACH_RCV_HEADER_ERROR

A message arrived, but its header transfer was incomplete

MACH_RCV_HEADER_ERROR is not the same as “no message.” The kernel has dequeued a message, but a resource shortage prevented it from transferring port rights carried in the header to the receiving task. The interface documents extra status bits that identify whether the shortage was IPC name-space space, virtual-address space, kernel IPC resources, or kernel virtual-memory resources.

This matters because an RPC server can receive a request whose header is only partially usable. The reply port or other rights expected by higher-level code may be absent or invalid. Continuing as though the request were normal can leak resources, reply to the wrong endpoint, or misclassify a system-pressure event as a client protocol error.

How to respond safely

Decode and log the additional MACH_MSG_IPC_SPACE, MACH_MSG_VM_SPACE, MACH_MSG_IPC_KERNEL, or MACH_MSG_VM_KERNEL bits.
Do not dispatch the request to ordinary application logic until required header rights are validated.
Apply memory and port-right pressure controls; a retry alone cannot create task name-space capacity.
Use cleanup that understands the message may already have been dequeued and partially transferred.

References

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