| Previous | Next |
| kIOUSBNotSent2Err | kIOUSBTooManyTransactionsPending |
kIOUSBLinkErr
The numeric result becomes useful only when tied to the exact operation and object state. The USB family reported a link/transaction condition at the host-controller or bus boundary rather than a class-driver application error.
Where the result is produced
IOKit results, internal tokens, and service messages cross user space, kernel services, and hardware families. Their integer representation does not make their control-flow roles interchangeable.
IOKit return values, internal tokens, and service messages share an integer representation but not the same control-flow meaning. Determine whether the API returns the value or delivers it as a message before treating it as failure. Keep the numeric value, declared return type, and first returning operation together with kIOUSBLinkErr; the same integer can belong to a different status namespace in another API.
Evidence to preserve
| Capture | Diagnostic value |
|---|---|
| Controller, port path, device address, speed, endpoint, transfer type, completion code, and bus generation. | Identifies the concrete object and operation associated with the result. |
| Numeric IOReturn/message value decoded with the matching SDK header. | Separates an argument or lifecycle state from a failure reported by the underlying provider. |
| Registry generation and first provider/client event before the result. | Provides a stable before/after comparison around the first provider or client event. |
| Known-good device or service state on the same macOS/driver build. | Shows whether the observed value is the primary result or a translated summary. |
Preserve registry generation and first provider/client event before the result for this result case before reinstalling, rebooting, clearing state, or substituting another device or provider. A success observed only after such a change is useful comparison data, but it does not identify the original cause.
A controlled diagnostic sequence
- Move the device to a known-good port/controller with the same cable and request. Treat a changed result as a new boundary rather than automatic resolution of this result.
- Change one topology or lifecycle condition while keeping the request payload fixed. Repeat the original supported operation so the check remains relevant to this result.
- Verify cleanup and object lifetime after the controlled operation. Keep unrelated inputs fixed so the change remains attributable to this result.
Correction and proof
Targeted correction. Repair signal, cable, power, hub, controller, or device link behavior before changing application protocol data. Modify only the object, argument, policy, provider, or lifecycle state identified by the collected evidence.
Acceptance criterion. The transfer completes on the original supported topology and repeated reconnects do not reproduce link failures. Re-run the original operation that produced this result under its original identity and supported configuration, then keep one negative control that still produces the expected neighboring outcome.
Technical references
References for kIOUSBLinkErr on the deployed platform version.
- Apple XNU: IOReturn definitions — defines the status namespace used.
- Apple: IOKit documentation — documents the API or lifecycle boundary behind this result.
- Apple OSS: XNU source — provides ABI, implementation, or protocol context.
- Apple XNU: FireWire family common definitions — supports the portability and verification limits.
Looking for a different code? Search another status or error code.