Problems with Marvel

Right now, I installed Marvel 2.x with Elasticsearch 2.3.1 and when I start up ES, I get the following error in the logs. Any clue as to how to solve it?

[2016-04-20 10:24:59,379][INFO ][marvel.agent.exporter ] [LOGSTASH-vx1e0c-D3] skipping exporter [default_local] as it isn't ready yet

Why is it skipping the exporter?

Whether I leave these lines commented or uncommented (in elasticsearch.yml), I keep getting that "skipping exporter".

marvel.agent.exporters:
id1:
type: http
host: ${ES_CLUSTER_HOSTS}

Apart from this, I get an error:

[.marvel-es-1-2016.04.20][[.marvel-es-1-2016.04.20][0]] [.marvel-es-1-2016.04.20][[.marvel-es-1-2016.04.20][0]] IllegalIndexShardStateException[CurrentState[POST_RECOVERY] operation only allowed when started/recovering, origin [PRIMARY]]
at org.elasticsearch.index.shard.IndexShard.ensureWriteAllowed(IndexShard.java:1068)
at org.elasticsearch.index.shard.IndexShard.create(IndexShard.java:538)
at org.elasticsearch.index.engine.Engine$Create.execute(Engine.java:810)
at org.elasticsearch.action.index.TransportIndexAction.executeIndexRequestOnPrimary(TransportIndexAction.java:237)
at org.elasticsearch.action.bulk.TransportShardBulkAction.shardIndexOperation(TransportShardBulkAction.java:326)
at org.elasticsearch.action.bulk.TransportShardBulkAction.shardOperationOnPrimary(TransportShardBulkAction.java:119)
at org.elasticsearch.action.bulk.TransportShardBulkAction.shardOperationOnPrimary(TransportShardBulkAction.java:68)
at org.elasticsearch.action.support.replication.TransportReplicationAction$PrimaryPhase.doRun(TransportReplicationAction.java:639)
at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37)
at org.elasticsearch.action.support.replication.TransportReplicationAction$PrimaryOperationTransportHandler.messageReceived(TransportReplicationAction.java:279)
at org.elasticsearch.action.support.replication.TransportReplicationAction$PrimaryOperationTransportHandler.messageReceived(TransportReplicationAction.java:271)
at org.elasticsearch.transport.RequestHandlerRegistry.processMessageReceived(RequestHandlerRegistry.java:75)
at org.elasticsearch.transport.TransportService$4.doRun(TransportService.java:376)
at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
[2016-04-20 11:11:36,956][DEBUG][action.bulk ] [LOGSTASH-vx1e0c-D1] failed to execute [BulkShardRequest to [.marvel-es-1-2016.04.20] containing [1] requests] on [[.marvel-es-1-2016.04.20][0]]

Could I get any help, please?