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NAP_E_INVALID_PACKET
The NAP Statement of Health packet is invalid
NAP_E_INVALID_PACKET is HRESULT 0x80270001 (signed decimal -2144927743, unsigned decimal 2150039553). AllStat, using winerror.h, describes it as “The NAP SoH packet is invalid.” The value has failure severity, facility 0x27, and code field 0x0001.
This is a legacy Network Access Protection result: Microsoft states that NAP is unavailable starting with Windows 10 and that current Windows Server releases do not include the former NAP, HRA, and HCAP roles; use the code for supported legacy systems, archived telemetry, compatibility components, or migrations rather than assuming a modern machine should expose the old platform.
What the validator has rejected
This result belongs to Statement of Health processing. A packet can be present and still fail validation because its encoding, attribute layout, lengths, request/response role, or required identifiers do not satisfy the NAP protocol contract. Microsoft specifically directs an SHV that receives a malformed SoHRequest to construct an SoHResponse carrying this code. The result therefore identifies packet validation, not a decision that the endpoint is unhealthy.
Typical packet defects
- A TLV length extends beyond the available buffer, an attribute is truncated, or nested data does not fit the declared size.
- The packet was constructed as an SoHResponse but is being validated as an SoHRequest, or the inverse role was supplied to the constructor validator.
- Required system-health identity or error attributes are absent, duplicated in an illegal position, or encoded with the wrong type.
- A transport or marshaling layer changed byte order, alignment, count fields, or the exact byte sequence after the SoH was signed or validated.
- A component reused a buffer after its lifetime ended and the consumer received partially overwritten packet data.
Evidence that distinguishes corruption from policy failure
- Record the packet direction, total byte count, request/response flag, SystemHealthEntityId, and the exact validation method that returned the HRESULT.
- Preserve a policy-approved hexadecimal capture of the malformed envelope or at least a hash plus per-attribute type and length; health payloads can contain sensitive posture data.
- Log the constructor/processor version, transport framing, correlation identifier, and whether validation failed before or after the packet crossed a process or network boundary.
- Compare the rejected packet with the last accepted packet from the same SHA or SHV, focusing on the first divergent attribute rather than only the final code.
Diagnostic sequence
- Run the same bytes through INapSoHConstructor::Validate with the correct isRequest value and stop at the first structural inconsistency.
- Rebuild the SoH from typed attributes instead of patching raw offsets, then verify all size fields after serialization.
- If corruption appears only after transport, capture the buffer immediately before send and immediately after receive and compare hashes and lengths.
- Confirm that failure-category and error-code attributes are used for component failure, while compliance-result attributes are used for an actual health verdict.
Difference from nearby NAP results
Do not confuse this code with NAP_E_MISSING_SOH. The missing-SoH result says the expected statement is absent; NAP_E_INVALID_PACKET says a supplied statement or envelope cannot be parsed or validated. It also differs from NAP_E_MISMATCHED_ID, where both messages may be structurally valid but belong to different exchanges.
Retry and recovery
Discard the malformed packet and repair the producer or marshaling path. Retrying identical bytes is not useful. A retry becomes meaningful only after the SoH is reconstructed, the transport defect is removed, or a new health exchange creates a fresh packet. Never salvage a packet by silently skipping an unknown or malformed field when the contract requires the complete authenticated structure.
Practical scenario
An SHA serializes a health attribute with a payload length copied from a character count rather than a byte count. The SHV receives the packet, detects that the attribute extends past the buffer, and reports NAP_E_INVALID_PACKET. The fix is in serialization; changing the health policy or treating the endpoint as noncompliant would diagnose the wrong layer.
References
- Microsoft: NAP error constants
- Microsoft: INapSoHConstructor::Validate
- Microsoft: INapSystemHealthValidator::Validate
- Microsoft: NAP interfaces
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