Since this is the second time I've ran into this problem - because its the second time I've done a nightmarish Play minor version upgrade - I'm posting this so it won't bite me again.

When I start seeing crashes during my tests that look something like this:

java.lang.AbstractMethodError: null  
    at$class.akka$actor$dungeon$FaultHandling$$finishTerminate(FaultHandling.scala:210) ~[akka-actor_2.10-2.3.4.jar:na]
    at$class.terminate(FaultHandling.scala:172) ~[akka-actor_2.10-2.3.4.jar:na]
    at ~[akka-actor_2.10-2.3.4.jar:na]
    at$1(ActorCell.scala:462) ~[akka-actor_2.10-2.3.4.jar:na]
    at ~[akka-actor_2.10-2.3.4.jar:na]
    at akka.dispatch.Mailbox.processAllSystemMessages(Mailbox.scala:263) ~[akka-actor_2.10-2.3.4.jar:na]
    at ~[akka-actor_2.10-2.3.4.jar:na]
    at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:393) [akka-actor_2.10-2.3.4.jar:na]
    at scala.concurrent.forkjoin.ForkJoinTask.doExec( [scala-library.jar:na]
    at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask( [scala-library.jar:na]
    at scala.concurrent.forkjoin.ForkJoinPool.runWorker( [scala-library.jar:na]
    at [scala-library.jar:na]

Then it means that one of my libraries has a binary dependency on Akka and needs to be updated to the latest version of Akka and compiled against it. Even better, if its actually one of my libraries then I just need to update and sbt publishLocal to verify that I am the root of the problem.