errno 42 (EUNATCH): meaning and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: Protocol driver not attached

Could be also:
Constant	Type	OS
KERN_SEMAPHORE_DESTROYED	Kern return	Mac
ippStsI18nGetMessageFail	Intel Ipp Status	Any
ENOMSG	errno	Linux
ENOPROTOOPT	errno	Mac
EILSEQ	errno	Windows
INCONSISTENT_IRP	BugCheck Code	Windows

Previous	Next
ENOPROTOOPT	EILSEQ

EUNATCH

The producer expected an attached protocol driver

EUNATCH is errno 42 in Solaris-compatible headers and is labeled Protocol driver not attached. Oracle's current errno catalog gives the label without assigning it to a general current syscall. POSIX does not define EUNATCH.

Unlike EPROTONOSUPPORT, this name describes an attachment state rather than absence of a protocol implementation. The exact meaning of “attached” belongs to the old subsystem that returns the value; it should not be replaced with generic advice to reinstall the network stack.

Find the missing attachment relationship

Trace the initialization or attach sequence of the driver, module, or compatibility subsystem that reports errno 42.
Record which protocol driver was expected and which lower/upper component requested it.
For imported logs, verify the Solaris/System V errno namespace before interpreting the numeric value as EUNATCH.

References

Looking for a different code? Search another status or error code.