What does HRESULT 0xC00E005E (MQ_ERROR_LABEL_BUFFER_TOO_SMALL) mean?

MQ_ERROR_LABEL_BUFFER_TOO_SMALL

Operational meaning

When MQ_ERROR_LABEL_BUFFER_TOO_SMALL appears, start with the queue operation and its property arrays rather than with a broad repair of the Message Queuing service. The result marks received label does not fit caller storage. The body may fit while the independent label buffer does not.

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

Variable-size MSMQ properties normally have a companion length property. The length returned after failure is evidence for allocation, not permission to process a truncated certificate, label, signature, or key.

Where the condition occurs

This is not automatically an out-of-memory condition. It describes caller-provided capacity for a particular returned property and often has a deterministic resize path. The code-specific boundary is received label does not fit caller storage.

Evidence to preserve

• Whether the operation consumed or retained the message.
• The property-specific length field returned by the same call.
• Declared capacity, returned required length, and element type.

Handling and recovery

Use the returned label length, resize, and repeat a peek before destructive receive.

Nearby failures

The condition is not evidence of low system memory. It describes the capacity and representation of one caller-owned output area. Code-specific condition: received label does not fit caller storage.

Worked example

A com/native interoperability layer encounters it. It uses the returned required length, keeps the operation non-destructive, and retries with correctly typed storage.

References

• Microsoft: MQReceiveMessageByLookupId
• Microsoft: Message Queuing error and information codes
• Microsoft: MSMQ message properties
• Microsoft: MQReceiveMessage