This error message is indicating that there is a mismatch between the configuration of a RabbitMQ queue and an exchange. Specifically, it is saying that the ‘x-dead-letter-exchange’ argument for the ‘simple.queue’ queue in the virtual host ‘/’ does not match the current value of ‘dl.direct’ (which is of type ‘longstr’).
The error code ‘406’ refers to a “PRECONDITION_FAILED” error, which means that some preconditions required for the operation to succeed were not met. In this case, it seems that the precondition is that the ‘x-dead-letter-exchange’ value for the queue must match the current value set for the exchange.
To resolve this issue, you will need to ensure that the ‘x-dead-letter-exchange’ value for the ‘simple.queue’ queue is set to ‘dl.direct’ (assuming that is the correct value). You can do this by modifying the configuration of the queue using the RabbitMQ management console or by using the appropriate API calls in your code. Once the queue and exchange configurations are aligned, this error should be resolved.