Under what conditions is it possible to fail to receive a message from the broker?

Unsuccessful message receipt by the broker can occur under the following conditions:

• Network issues: loss of connection between the sender and the broker or between the broker and the receiver.
• Broker overload: if the broker cannot handle the load, messages may be lost or delayed.
• Incorrect configuration of queues or topics, such as wrong access rights.
• Errors in the consumer's code, which prevent it from correctly processing or acknowledging message receipt.
• Use of unsafe delivery modes (e.g., "at most once"), where messages can be lost.
• Problems with message serialization/deserialization.

Example: if in RabbitMQ the consumer does not acknowledge receipt of a message (ack), and the broker is configured to delete messages after acknowledgment, then in case of consumer failure, the message may be lost.