Mongo Connection issue with error “state should be: open”

I am running an event in Akka actor system, where we run multiple actors to query mongo db and retrieve data. Each actor queries for 1000 documents (each document’s size is 9kb)

When running an event that is required to fire 14 actors to query for Mongo DB to retrieve 13000 documents.Once I experienced below exception, not sure why? Have anyone experienced this before?

2020-04-14 19:17:28,818 [erp-writer-actor-system-akka.actor.default-dispatcher-378] ERROR c.a.s.c.m.GlobalContextMongoClientService- 76cd7a80-83ef-4389-885a-be9caed77449 - Exception occured while reading data from cursor
java.lang.IllegalStateException: state should be: open
at com.mongodb.assertions.Assertions.isTrue(Assertions.java:70)
at com.mongodb.connection.DefaultServer.getConnection(DefaultServer.java:84)
at com.mongodb.binding.ClusterBinding$ClusterBindingConnectionSource.getConnection(ClusterBinding.java:86)
at com.mongodb.operation.QueryBatchCursor.getMore(QueryBatchCursor.java:203)
at com.mongodb.operation.QueryBatchCursor.hasNext(QueryBatchCursor.java:103)
at com.mongodb.MongoBatchCursorAdapter.hasNext(MongoBatchCursorAdapter.java:46)
at com.xyz.smartconnect.commons.mongoclient.GlobalContextMongoClientService.findWorkers(GlobalContextMongoClientService.java:145)
at com.xyz.smartconnect.actors.QueryWorkersActor.lambda$createReceive$0(QueryWorkersActor.java:40)
at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:26)
at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:21)
at scala.PartialFunction$class.applyOrElse(PartialFunction.scala:123)
at akka.japi.pf.UnitCaseStatement.applyOrElse(CaseStatements.scala:21)
at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:170)
at akka.actor.Actor$class.aroundReceive(Actor.scala:513)
at akka.actor.AbstractActor.aroundReceive(AbstractActor.scala:132)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:519)
at akka.actor.ActorCell.invoke(ActorCell.scala:488)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:257)
at akka.dispatch.Mailbox.run(Mailbox.scala:224)
at akka.dispatch.Mailbox.exec(Mailbox.scala:234)
at akka.dispatch.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at akka.dispatch.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at akka.dispatch.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at akka.dispatch.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Suppressed: java.lang. IllegalStateException: state should be: open
at com.mongodb.assertions.Assertions.isTrue(Assertions.java:70)
at com.mongodb.connection.DefaultServer.getConnection(DefaultServer.java:84)
at com.mongodb.binding.ClusterBinding$ClusterBindingConnectionSource.getConnection(ClusterBinding.java:86)
at com.mongodb.operation.QueryBatchCursor.killCursor(QueryBatchCursor.java:261)
at com.mongodb.operation.QueryBatchCursor.close(QueryBatchCursor.java:147)
at com.mongodb.MongoBatchCursorAdapter.close(MongoBatchCursorAdapter.java:41)
at com.xyz.smartconnect.commons.mongoclient.GlobalContextMongoClientService.findWorkers(GlobalContextMongoClientService.java:149)