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kIOReturnIOError
A transfer failure category, not a root cause
kIOReturnIOError is the common IOKit “General I/O error” status. It indicates that an I/O operation failed, but it does not tell whether the reason was device state, transport, media, controller behavior, a lower driver, or a family-specific request path. The actual IOKit family and operation are required to interpret it.
Use it differently from kIOReturnIPCError, which identifies the communication path, and from kIOReturnDeviceError, whose label explicitly points at a device not working properly. A generic I/O error should retain all available per-request information before a retry, reset, or user-facing translation is chosen.
What to inspect
- Record operation direction, request size, target service, active mode, timeout policy, and any partial-completion information.
- Check preceding power, removal, reset, or configuration events that can invalidate a previously valid request.
- Correlate application logs with the responsible IOKit family or driver diagnostics.
- Retry only when the operation is known to be safe to repeat and the target has been revalidated.
References
- Apple XNU source: IOReturn.h
- Apple: Introduction to IOKit Fundamentals
- Apple: Managing data in IOKit
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