errno 136 (EPROTOTYPE): meaning and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: A UCRT POSIX-supplement status indicating that a protocol was requested with a socket type that cannot use it.

Could be also:
Constant	Type	OS
ERROR_NOT_JOINED	Win32 error	Windows

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EPROTONOSUPPORT	ETIMEDOUT

EPROTOTYPE

EPROTOTYPE identifies an incompatible protocol-and-socket-type pair. A protocol can exist on the machine and an address family can be supported, while the selected combination still makes no sense: for example, a message-oriented protocol where a stream endpoint was requested, or a stream protocol where a datagram endpoint was requested.

Native Windows socket code normally reports WSAEPROTOTYPE via WSAGetLastError(). The POSIX-style constant is useful for cross-platform code, but the diagnostic must retain the original socket arguments and any provider chosen by the implementation.

Separate three different errors

EAFNOSUPPORT concerns the address family.
EPROTONOSUPPORT concerns whether the protocol is available.
EPROTOTYPE concerns whether that available protocol fits the requested socket type.
Log all three creation parameters before deciding which layer needs correction.

References

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