errno 81 (ENEEDAUTH): meaning and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: the operation requires an authenticator before it can continue; identify the component that must obtain or present it.

Could be also:
Constant	Type	OS
ELIBSCN	errno	Linux
EBADFD	errno	Solaris
REGISTRY_ERROR	BugCheck Code	Windows

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ELIBSCN	EBADFD

ENEEDAUTH

ENEEDAUTH is a Darwin errno for an operation that cannot proceed until an authenticator is available. In the BSD errno tradition, it described an authentication ticket required before mounting a protected NFS file system. Apple’s current error-constant documentation maps it to needAuthenticator, and FSKit uses it when a file-system container needs authentication.

This is a prerequisite state, not proof that a supplied credential was invalid. The component that returned the code is expected to know what counts as an authenticator and how it is acquired. It may need to start an authentication flow, select an identity, obtain a ticket, or request user interaction; changing ordinary POSIX mode bits is unrelated unless the same API documents that connection.

Keep the authentication states separate

This result: no usable authenticator is available for the required step.
EAUTH: authentication was attempted but failed or was rejected.
EACCES: access was denied; this alone does not show that an authenticator was requested.

Focused diagnostic steps

Identify the exact API that produced this result and whether it permits an interactive authentication flow. A daemon, login item, or command running without a GUI session may need a different handoff mechanism than an app in the foreground.
Record the resource, provider, identity-selection context, and caller mode, but exclude credential material from logs. The useful distinction is between “no authenticator was requested”, “one was unavailable”, and “one was supplied and rejected”.
For protected network mounts, keep the server and export identity with the error. Obtaining a credential for a similarly named but different service does not satisfy the original mount request.
Retry only after the component can obtain or receive the required authenticator. A blind retry of the same noninteractive call normally preserves the missing precondition.

References

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