akka-kryo-serialization ClassNotFoundException：scala.Enumeration $ Val

Question

Sometimes when updating a dependency version for my project, when I would run the project I would get the following error:

ERROR 09:31:34:241 apply$mcV$sp - Class could not be loaded and/or registered: scala.Enumeration$Val 
ERROR 09:31:34:247 apply$mcV$sp - exception caught during akka-kryo-serialization startup: java.lang.ClassNotFoundException: scala.Enumeration$Val
java.lang.RuntimeException: Nonzero exit code: 1
at scala.sys.package$.error(package.scala:27)

I usually got lucky and was able to fix this by tweaking the versions of my dependencies.

Until I updated my akka version from 2.3.6 to 2.3.12, specifically akka-contrib which contains akka-cluster, akka-remote and akka-peristance.

Answer 1

Turns out that the problem was actually occurring during the transition between akka 2.3.8 and 2.3.9. Looking at the change log, I found that between these two versions the Scala version was upgraded from 2.11.4 to 2.11.5.

My project was building on scala 2.11.4. Upgrading to 2.11.5 fixed the problem.

I couldn't find any help online for this, and lost a couple days trying to figure this out. I'm hoping that this will help someone else out.