When a configured journal plugin is missing from the classpath, the following exception is thrown:

11:23:37.614 [kiarchive-akka.actor.default-dispatcher-19] ERROR akka.actor.OneForOneStrategy - actor name [snapshot-store] is not unique!
akka.actor.ActorInitializationException: exception during creation
at akka.actor.ActorInitializationException$.apply(Actor.scala:164) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ActorCell.create(ActorCell.scala:596) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ActorCell.invokeAll$1(ActorCell.scala:456) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ActorCell.systemInvoke(ActorCell.scala:478) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.dispatch.Mailbox.processAllSystemMessages(Mailbox.scala:263) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.dispatch.Mailbox.run(Mailbox.scala:219) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) ~[na:1.7.0_09-icedtea]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) ~[na:1.7.0_09-icedtea]
at java.lang.Thread.run(Thread.java:722) ~[na:1.7.0_09-icedtea]
Caused by: akka.actor.InvalidActorNameException: actor name [snapshot-store] is not unique!
at akka.actor.dungeon.ChildrenContainer$NormalChildrenContainer.reserve(ChildrenContainer.scala:130) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.dungeon.Children$class.reserveChild(Children.scala:77) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ActorCell.reserveChild(ActorCell.scala:369) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.dungeon.Children$class.makeChild(Children.scala:202) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.dungeon.Children$class.attachChild(Children.scala:42) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ActorCell.attachChild(ActorCell.scala:369) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ActorSystemImpl.systemActorOf(ActorSystem.scala:550) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.persistence.Persistence.createPlugin(Persistence.scala:148) ~[com.typesafe.akka.akka-persistence-experimental_2.10-2.3.0.jar:na]
at akka.persistence.Persistence.<init>(Persistence.scala:87) ~[com.typesafe.akka.akka-persistence-experimental_2.10-2.3.0.jar:na]
at akka.persistence.Persistence$.createExtension(Persistence.scala:73) ~[com.typesafe.akka.akka-persistence-experimental_2.10-2.3.0.jar:na]
at akka.persistence.Persistence$.createExtension(Persistence.scala:67) ~[com.typesafe.akka.akka-persistence-experimental_2.10-2.3.0.jar:na]
at akka.actor.ActorSystemImpl.registerExtension(ActorSystem.scala:698) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ExtensionId$class.apply(Extension.scala:79) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.persistence.Persistence$.apply(Persistence.scala:67) ~[com.typesafe.akka.akka-persistence-experimental_2.10-2.3.0.jar:na]
at akka.persistence.snapshot.SnapshotStore$class.$init$(SnapshotStore.scala:21) ~[com.typesafe.akka.akka-persistence-experimental_2.10-2.3.0.jar:na]
at akka.persistence.snapshot.local.LocalSnapshotStore.<init>(LocalSnapshotStore.scala:26) ~[com.typesafe.akka.akka-persistence-experimental_2.10-2.3.0.jar:na]
at sun.reflect.GeneratedConstructorAccessor2.newInstance(Unknown Source) ~[na:na]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.7.0_09-icedtea]
at java.lang.reflect.Constructor.newInstance(Constructor.java:525) ~[na:1.7.0_09-icedtea]
at java.lang.Class.newInstance0(Class.java:372) ~[na:1.7.0_09-icedtea]
at java.lang.Class.newInstance(Class.java:325) ~[na:1.7.0_09-icedtea]
at akka.util.Reflect$.instantiate(Reflect.scala:45) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.NoArgsReflectConstructor.produce(Props.scala:358) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.Props.newActor(Props.scala:249) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ActorCell.newActor(ActorCell.scala:552) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
at akka.actor.ActorCell.create(ActorCell.scala:578) ~[com.typesafe.akka.akka-actor_2.10-2.3.0.jar:na]
... 7 common frames omitted

This does not really tell, what the cause of the exception is. Maybe a more explicit exception should be thrown.