Sentinel Errors

rabbitmq.ErrConnectionClosed  // Connection is closed
rabbitmq.ErrChannelClosed     // Channel is closed
rabbitmq.ErrPublishFailed     // Publish operation failed
rabbitmq.ErrConsumeFailed     // Consume operation failed
rabbitmq.ErrInvalidConfig     // Invalid configuration
rabbitmq.ErrNotConnected      // Not connected
rabbitmq.ErrTimeout           // Operation timeout
rabbitmq.ErrNack              // Message was nacked
rabbitmq.ErrMaxReconnects     // Max reconnection attempts reached (see OnReconnectAborted)
rabbitmq.ErrShuttingDown      // Shutting down
rabbitmq.ErrNilConnection     // A nil connection was passed to a constructor
rabbitmq.ErrNilMessage        // A nil message was passed to a publish call
rabbitmq.ErrDelayTooLong      // PublishDelayed's delay exceeds the largest ladder rung

if errors.Is(err, rabbitmq.ErrConnectionClosed) {
    // Handle...
}

Two more are handler-facing, not returned by the package itself — return them from a Consume handler to override the RequeueOnError default for that one message (see Middleware → Error Handling):

rabbitmq.ErrRequeue // requeue and retry
rabbitmq.ErrDrop    // never requeue (dead-letter/discard)

Consumer.Start and Close/CloseWithContext have their own sentinels — ErrAlreadyConsuming, ErrConsumerTagInUse from Start, ErrChannelBusy from Close — documented alongside the methods that return them in Consuming Messages.