What does HRESULT 0xC00E0046 (MQ_ERROR_RESULT_BUFFER_TOO_SMALL) mean?

MQ_ERROR_RESULT_BUFFER_TOO_SMALL

Interpretation

The important part of MQ_ERROR_RESULT_BUFFER_TOO_SMALL is not only whether the call failed, but which MSMQ subsystem had enough information to return this specific result. Interpret it as MQLocateNext cannot return one complete row, not as a general transport outage. The result buffer must accommodate at least one full projected result, not merely part of a row.

For MQ_ERROR_RESULT_BUFFER_TOO_SMALL, variable-size MSMQ properties normally have a companion length property. When diagnosing MQ_ERROR_RESULT_BUFFER_TOO_SMALL, the length returned after failure is evidence for allocation, not permission to process a truncated certificate, label, signature, or key.

When diagnosing MQ_ERROR_RESULT_BUFFER_TOO_SMALL, buffer capacity should be logged in bytes or characters exactly as the API defines it. In the MQ_ERROR_RESULT_BUFFER_TOO_SMALL path, converting lengths between UTF-16 characters, bytes, and array elements is a common source of repeated failures.

Relevant API contract

When diagnosing MQ_ERROR_RESULT_BUFFER_TOO_SMALL, this is not automatically an out-of-memory condition. In the MQ_ERROR_RESULT_BUFFER_TOO_SMALL path, it describes caller-provided capacity for a particular returned property and often has a deterministic resize path. For MQ_ERROR_RESULT_BUFFER_TOO_SMALL, the code-specific boundary is MQLocateNext cannot return one complete row.

Decisive observations

• Whether the operation consumed or retained the message; associate it explicitly with MQ_ERROR_RESULT_BUFFER_TOO_SMALL.
• When diagnosing MQ_ERROR_RESULT_BUFFER_TOO_SMALL, the property-specific length field returned by the same call; capture the value before cleanup or retry changes it.
• In the MQ_ERROR_RESULT_BUFFER_TOO_SMALL path, declared capacity, returned required length, and element type; compare it with a known-good call using the same account and queue type.
• For this MQ_ERROR_RESULT_BUFFER_TOO_SMALL 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_RESULT_BUFFER_TOO_SMALL, 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.

Troubleshooting workflow

1. Record the unsigned HRESULT, MQ_ERROR_RESULT_BUFFER_TOO_SMALL, and the native API or COM method before a framework replaces it with a generic exception.
2. When diagnosing MQ_ERROR_RESULT_BUFFER_TOO_SMALL, capture the property-specific length field returned by the same call.
3. In the MQ_ERROR_RESULT_BUFFER_TOO_SMALL path, capture declared capacity, returned required length, and element type.
4. Reproduce with the smallest queue/message/property set that still returns MQ_ERROR_RESULT_BUFFER_TOO_SMALL; change one precondition at a time.
5. For MQ_ERROR_RESULT_BUFFER_TOO_SMALL, verify the postcondition after the failed call: queue existence, message presence, directory object state, transaction outcome, or generated output may differ by result.
6. When diagnosing MQ_ERROR_RESULT_BUFFER_TOO_SMALL, apply the code-specific recovery rule: Increase the row/result storage or reduce projected variable-length columns.

Recovery rules

Increase the row/result storage or reduce projected variable-length columns.

When diagnosing MQ_ERROR_RESULT_BUFFER_TOO_SMALL, the retry decision must account for side effects that may already exist. In the MQ_ERROR_RESULT_BUFFER_TOO_SMALL path, query queue, message, directory, or transaction state first whenever the result leaves completion uncertain.

Differences that matter

In the MQ_ERROR_RESULT_BUFFER_TOO_SMALL path, the condition is not evidence of low system memory. For this MQ_ERROR_RESULT_BUFFER_TOO_SMALL result, it describes the capacity and representation of one caller-owned output area. The specific focus for MQ_ERROR_RESULT_BUFFER_TOO_SMALL remains MQLocateNext cannot return one complete row.

• In the MQ_ERROR_RESULT_BUFFER_TOO_SMALL path, changing queue names, deleting directory objects, or recreating certificates without reconciliation can create a second object while callers still reference the first.
• For this MQ_ERROR_RESULT_BUFFER_TOO_SMALL result, A successful test under an interactive administrator account does not prove that the production service account has the same profile, token, directory access, or key permissions.

Practical scenario

A receiver that sizes output buffers encounters MQ_ERROR_RESULT_BUFFER_TOO_SMALL. For MQ_ERROR_RESULT_BUFFER_TOO_SMALL, it uses the returned required length, keeps the operation non-destructive, and retries with correctly typed storage. When diagnosing MQ_ERROR_RESULT_BUFFER_TOO_SMALL, the acceptance test then changes only the decisive precondition and confirms both the HRESULT and the actual queue/message state.

A regression test should force MQ_ERROR_RESULT_BUFFER_TOO_SMALL, assert the raw value and relevant outputs, then correct only the documented precondition and verify the intended success or neighboring HRESULT.

Sources

• Microsoft: MSMQ message properties — source used for the MQ_ERROR_RESULT_BUFFER_TOO_SMALL analysis.
• Microsoft: MQReceiveMessage — source used for the MQ_ERROR_RESULT_BUFFER_TOO_SMALL analysis.
• Microsoft: MQReceiveMessageByLookupId — source used for the MQ_ERROR_RESULT_BUFFER_TOO_SMALL analysis.
• Microsoft: Message Queuing error and information codes — source used for the MQ_ERROR_RESULT_BUFFER_TOO_SMALL analysis.

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