[error] akka.actor.OneForOneStrategy [sourceThread=application-akka.actor.default-dispatcher

[error] akka.actor.OneForOneStrategy [sourceThread=application-akka.actor.default-dispatcher-3, akkaTimestamp=05:56:56.431UTC, akkaSource=akka://application/user/readSideGlobalPrepareEventsProcessor-singleton/singleton/readSideGlobalPrepare-EventsProcessor, sourceActorSystem=-application] - null
java.lang.NullPointerException: null

akka.pattern.AskTimeoutException: Ask timed out on [Actor[akka://application/user/readSideGlobalPrepare-EventsProcessor-singletonProxy#-1824296709]] after [20000 ms]. Sender[null] sent message of type “com.lightbend.lagom.internal.persistence.cluster.ClusterStartupTaskActor$Execute$”.

Can anyone please help me with this error,
Note : I am using lagom framework.

Thanks in advance.