[Solved]-Akka Dead Letters with Ask Pattern-scala

The reason is because the value of 'sender' (which is a method that retrieves the value) is no longer valid after leaving the receive block, yet the future that is being used in the above example will still be running and by the time that it finishes the actor will have left the receive block and bang; an invalid sender results in the message going to the dead letter queue.

The fix is to either not use a future, or when combining futures, actors and sender then capture the value of sender before you trigger the future.

val s = sender

val responseFuture = get(lastrun)
    responseFuture.onSuccess {    
    ....
    s ! time
}