@mateiz  hmm, I don't quite catch you. Do you mean akka 2.3 work well with spark? I don't run in big cluster, so I am not sure about the stability issue mentioned in the akka downgrade thread. Or you mean akka 2.3 work well with protobuf 2.5? then yes,akka 2.3-M1 move to protobuf 2.5, at least it's build file say so ;)