Dead letter from publisher to mediator in Classic DistributedPubSub

Hi all,

I have a publisher extension and subscriber extension on the same node, both accessing a distributed pubsub mediator extension.
The subscriber has successfully subscribed to a single topic, as noted by subscribe acks.
The publisher attempts to publish to the same topic, via the mediator, using mediator.tell(Publish(…)
At this point, a dead letter occurs. The logs say the message could not be delivered to the mediator, and that the mediator may have terminated.

I have attempted the following:

  1. retrieve the mediator extension immediately before sending the message.
  2. try multiple serialization formats for the message
  3. ensure the subscriber is expecting the message type sent by the publisher
  4. resend the message periodically

None of these approaches have solved this issue. Does anyone have an idea of what is causing the message to not be delivered to the mediator?

Additionally, the publisher has subscribed to another message type that it sends to itself periodically via mediator.tell(Publish(…)), and this always succeeds.

Figured it out, the topic name being published to was not matching the subscribed name… The difference was quotations. I saw this in the logs but did not realize the quotes were part of the topic name…