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ERROR_NDIS_OFFLOAD_CONNECTION_REJECTED
TCP Chimney target rejected a connection identifies a scoped API or runtime boundary rather than a general machine failure. The offload target declined the particular TCP connection after the host considered it for offload.
Read the status in context
TCP offload is an optimization below a valid host TCP connection. An offload refusal can coexist with correct host-stack transport, so eligibility and data transfer need separate checks.
The local policy may permit offload and the IP path may be valid; this result is the target-specific decision for one connection. Keep the numeric value, declared return type, and first returning operation together with ERROR_NDIS_OFFLOAD_CONNECTION_REJECTED; the same integer can belong to a different status namespace in another API.
Diagnostic facts
| Capture | Diagnostic value |
|---|---|
| Connection state, TCP options, target capabilities, adapter/driver version, and offload block list. | Identifies the concrete object and operation associated with TCP Chimney target rejected a connection. |
| Target completion status and whether neighboring connections on the same path offload. | Separates argument or lifecycle state from a lower-layer provider failure. |
| ETW/network trace showing the first offload eligibility decision. | Creates a stable before-and-after comparison. |
| Known-good connection and adapter state captured on the same Windows build. | Shows whether this condition is the first result or a translated summary. |
Preserve known-good connection and adapter state captured on the same Windows build while evaluating this condition 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.
Verification path
- Test a simple connection without unusual TCP options to the same peer. Repeat the original supported operation so the check remains tied to the same API boundary.
- Query target capabilities and compare the rejected connection attributes. Keep unrelated inputs fixed so the changed result remains attributable to the tested variable.
- Verify data transfer correctness with offload disabled as a control. Record the first returned status and any state transition observed.
What the result does not prove
| Observed comparison | Next conclusion to test |
|---|---|
| The first control changes the result | Concentrate on the variable isolated by this check: Test a simple connection without unusual TCP options to the same peer. |
| The second comparison reproduces the same first status | Preserve lower-layer provider, driver, service, or runtime evidence before editing application data. The second controlled check was: Query target capabilities and compare the rejected connection attributes. |
| A different status appears after the bounded change | The operation moved to another boundary after the third controlled check. That check was: Verify data transfer correctness with offload disabled as a control. Retain both results and interpret the replacement through its own API contract. |
Closing the incident
Targeted correction. Update or configure the target driver, remove unsupported connection features where safe, or keep the connection on the host stack. Modify only the object, argument, policy, provider, or lifecycle state identified by the collected evidence.
Acceptance criterion. Supported connections offload reliably and rejected ones fall back without reset, data loss, or retry storms. Re-run the original operation that produced this condition under its original identity and supported configuration, then keep one negative control that still produces the expected neighboring outcome.
Technical references
References for ERROR_NDIS_OFFLOAD_CONNECTION_REJECTED on the deployed platform version.
- Microsoft Open Specifications: HRESULT values — defines the status namespace used.
- Microsoft: HRESULT facility extraction — documents the API or lifecycle boundary behind this condition.
- Microsoft: full TCP offload — provides ABI, implementation, or protocol context.
- Microsoft: NDIS Chimney interfaces — supports the portability and verification limits.
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