What does macOS kernel return 0x10004011 (MACH_RCV_IN_PROGRESS_TIMED) mean?

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: Internal Mach state for a thread waiting on a receive operation that has a timeout.

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MACH_RCV_INVALID_TRAILER	MACH_RCV_INVALID_REPLY

MACH_RCV_IN_PROGRESS_TIMED

A timed wait state, not a timeout result

MACH_RCV_IN_PROGRESS_TIMED is marked internal-use only in current XNU headers. It records that a receive thread is waiting with timeout behavior active. The public result after the interval expires is MACH_RCV_TIMED_OUT; if a message arrives first, the operation can complete successfully instead.

Confusing the two values creates premature retries and duplicate receive workers. The internal state may appear in kernel debugging, wait-state telemetry, or private code, but it is not a durable API result for applications to serialize or compare across OS versions.

What to inspect

Capture the requested timeout, receive options, start time, and final return value.
Account for documented interruption and automatic-retry behavior when measuring elapsed time.
Check whether the port or port set has producers and whether membership changed while the thread waited.
Use MACH_RCV_TIMED_OUT for ordinary timeout handling; reserve this symbol for interpreting internal diagnostics.

References

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