What does HRESULT 0xC00E0079 (MQ_ERROR_PUBLIC_KEY_NOT_FOUND) mean?

MQ_ERROR_PUBLIC_KEY_NOT_FOUND

Operational meaning

MQ_ERROR_PUBLIC_KEY_NOT_FOUND belongs to the Message Queuing HRESULT facility, but its useful meaning is narrower than a generic messaging failure. In this case the decisive subject is requested enhanced key unavailable on older-capability computer. The directory query succeeded, but the target supports only the legacy encryption capability.

For MQ_ERROR_PUBLIC_KEY_NOT_FOUND, encryption capability and message authentication are related but distinct. When diagnosing MQ_ERROR_PUBLIC_KEY_NOT_FOUND, preserve provider, algorithm, certificate, key-container, and queue authentication/privacy settings rather than collapsing them into one “SSL” diagnosis.

When diagnosing MQ_ERROR_PUBLIC_KEY_NOT_FOUND, MSMQ security material can live in the current user profile and be registered in directory services. In the MQ_ERROR_PUBLIC_KEY_NOT_FOUND path, services running under another account or without a loaded profile can observe a different certificate-store state.

Where to draw the boundary

When diagnosing MQ_ERROR_PUBLIC_KEY_NOT_FOUND, queue ACLs, certificate trust, private-key access, provider support, and destination authentication policy are independent. Test the layer named by the evidence. For MQ_ERROR_PUBLIC_KEY_NOT_FOUND, the code-specific boundary is requested enhanced key unavailable on older-capability computer.

Evidence to preserve

• Certificate store location and security identity used by the process; associate it explicitly with MQ_ERROR_PUBLIC_KEY_NOT_FOUND.
• When diagnosing MQ_ERROR_PUBLIC_KEY_NOT_FOUND, provider name/type, hash algorithm, and privacy/authentication properties; capture the value before cleanup or retry changes it.
• In the MQ_ERROR_PUBLIC_KEY_NOT_FOUND path, whether the failure occurred while preparing, sending, storing, or validating the message; compare it with a known-good call using the same account and queue type.
• For this MQ_ERROR_PUBLIC_KEY_NOT_FOUND result, record the queue path or format name, local/remote placement, transactional flag, caller SID, process build, and UTC correlation ID when they apply.

For MQ_ERROR_PUBLIC_KEY_NOT_FOUND, log certificate thumbprints, provider names, SIDs, GUIDs, lengths, and hashes where useful, but do not log private keys, symmetric keys, credentials, or confidential message bodies.

Diagnostic sequence

1. Record the unsigned HRESULT, MQ_ERROR_PUBLIC_KEY_NOT_FOUND, and the native API or COM method before a framework replaces it with a generic exception.
2. Reproduce with the smallest queue/message/property set that still returns MQ_ERROR_PUBLIC_KEY_NOT_FOUND; change one precondition at a time.
3. In the MQ_ERROR_PUBLIC_KEY_NOT_FOUND path, verify the postcondition after the failed call: queue existence, message presence, directory object state, transaction outcome, or generated output may differ by result.
4. For this MQ_ERROR_PUBLIC_KEY_NOT_FOUND result, capture whether the failure occurred while preparing, sending, storing, or validating the message.
5. For MQ_ERROR_PUBLIC_KEY_NOT_FOUND, capture certificate store location and security identity used by the process.
6. When diagnosing MQ_ERROR_PUBLIC_KEY_NOT_FOUND, apply the code-specific recovery rule: Negotiate a compatible privacy level or upgrade the destination MSMQ capability.

Handling and recovery

Negotiate a compatible privacy level or upgrade the destination MSMQ capability.

When diagnosing MQ_ERROR_PUBLIC_KEY_NOT_FOUND, retry only after a measurable state change: corrected property data, resized storage, restored service/directory reachability, recreated handle, completed transaction recovery, or repaired certificate access. In the MQ_ERROR_PUBLIC_KEY_NOT_FOUND path, bound attempts and keep an idempotency key for sends or directory mutations.

Nearby failure boundaries

In the MQ_ERROR_PUBLIC_KEY_NOT_FOUND path, authentication failure is not synonymous with queue access denial. For this MQ_ERROR_PUBLIC_KEY_NOT_FOUND result, certificate stores, private keys, providers, signatures, and queue policy must be tested separately. The specific focus for MQ_ERROR_PUBLIC_KEY_NOT_FOUND remains requested enhanced key unavailable on older-capability computer.

• In the MQ_ERROR_PUBLIC_KEY_NOT_FOUND path, restarting MSMQ before collecting evidence can invalidate handles and erase the first useful event; it is a containment action, not a root-cause diagnosis.
• For this MQ_ERROR_PUBLIC_KEY_NOT_FOUND result, granting broad queue or certificate permissions may mask the symptom while creating a security defect. For MQ_ERROR_PUBLIC_KEY_NOT_FOUND, test the exact identity and access needed by the operation.

Worked example

A service sending authenticated messages encounters MQ_ERROR_PUBLIC_KEY_NOT_FOUND. For MQ_ERROR_PUBLIC_KEY_NOT_FOUND, it tests store and private-key access under the production identity before changing queue security. When diagnosing MQ_ERROR_PUBLIC_KEY_NOT_FOUND, the acceptance test then changes only the decisive precondition and confirms both the HRESULT and the actual queue/message state.

For MQ_ERROR_PUBLIC_KEY_NOT_FOUND, include a negative test for the nearest misleading diagnosis so monitoring and user guidance do not collapse distinct MSMQ failures into one alert.

References

• Microsoft: Windows certificate stores — source used for the MQ_ERROR_PUBLIC_KEY_NOT_FOUND analysis.
• IETF RFC 5280: Internet X.509 PKI certificate profile — source used for the MQ_ERROR_PUBLIC_KEY_NOT_FOUND analysis.
• Microsoft: Message Queuing error and information codes — source used for the MQ_ERROR_PUBLIC_KEY_NOT_FOUND analysis.
• Microsoft: authenticated MSMQ message with an external certificate — source used for the MQ_ERROR_PUBLIC_KEY_NOT_FOUND analysis.
• Microsoft: MSMQMessage object and message properties — source used for the MQ_ERROR_PUBLIC_KEY_NOT_FOUND analysis.

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