NTSTATUS 259 (STATUS_PENDING): meaning and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: The request was accepted and will complete asynchronously.

Could be also:
Constant	Type	OS
ERROR_NO_MORE_ITEMS	Win32 error	Windows
MUP_FILE_SYSTEM	BugCheck Code	Windows

Previous	Next
STATUS_TIMEOUT	STATUS_REPARSE

STATUS_PENDING

The operation will complete asynchronously

STATUS_PENDING transfers completion responsibility to a later path. In driver I/O, a lower driver can mark an IRP pending and complete it after the dispatch routine returns. User-mode native calls can likewise report pending while an event, APC, or I/O completion mechanism will deliver the final result.

The value is not the final success or failure status. Buffers, events, file objects, callback contexts, and the I/O status block must remain valid until completion. Reading output immediately or completing the same IRP from two paths produces races and memory corruption.

What to inspect

Identify the completion mechanism and the object that owns the request after the pending return.
Propagate pending state correctly through layered drivers with IoMarkIrpPending when required.
Keep every referenced buffer and context alive until the final completion callback runs.
Log both the initial pending result and the later final status under one request identifier.

References

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