Hi Jeroen, Thanks for preparing the example, it made checking what the problem is very simple :-)
Try searching for `confirmDelivery` in your code snippet. It's not there. And with no confirmation, there is no information on in the sending-actor that the target has really received the message. The interaction MUST be such that: [bob] [alice] m(1) -------------X # message lost! m(1) ------------------> got m(1) # message got here X---------------- confirm 1 # confirmation lost! # re-send triggers m(1) -------------------> got m(1) # "oh, I know it already!" confirmDelivery(1) <----- confirm 1 # confirmation got to sender At least once delivery semantics imply two things: 1) the receiver must be ready to receive the message multiple times (should simply ignore if it knows it already, or the messages should be idempotent <http://en.wikipedia.org/wiki/Idempotence>). 2) the sender must retry sending a message until it gets a confirmation back from the receiver In your case you forgot the 2) rule. AtLeastOnceDelivery has helpers for this, in form of: confirmDelivery. Please read the example in the docs in detail: http://doc.akka.io/docs/akka/snapshot/scala/persistence.html#at-least-once-delivery I would also highly recommend watching my or Endre's talks which are * "without past or present" by Endre http://letitcrash.com/post/83823246588/without-past-and-present * "distributed consensus aka. what do we eat for lunch" by me http://letitcrash.com/post/98879157982/introduction-to-distributed-consensus-by-konrad They have videos and slides, I hope you'll enjoy it (great watch right in time for a friday evening?)! Happy hakking! -- Cheers, Konrad 'ktoso' Malawski hAkker @ Typesafe <http://typesafe.com> -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at http://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.