<p>I have a Lagom microservice, running on Kubernetes with 3 PODs. It is not able to form a cluster on startup and keeps on displaying the following message:</p>

<blockquote>
  <p>2019-07-12T19:29:27.310Z WARN akka.cluster.sharding.ShardRegion - Trying to register to coordinator at [ActorSelection[Anchor(akka.tcp://microservice@10.233.101.14:10001/), Path(/system/sharding/MicroserviceEventProcessorCoordinator/singleton/coordinator)]], but no acknowledgement. Total [1580] buffered messages. [Coordinator [Member(address = akka.tcp://microservice@10.233.101.14:10001, status = Up)] is reachable.]</p>
</blockquote>

<p>Also the number of <code>buffered messages</code> is constantly increasing. Since there is no documentation for such behavior of a Lagom microservice, can anyone help me in understanding and fixing this issue?</p>

himanshuIIITian
<p>I was not able to find a definitive answer to this issue. But following configurations solved the issue:</p>

<blockquote>
  <p>sharding.state-store-mode = ddata</p>
</blockquote>

<p>and</p>

<pre><code>serialization-bindings {
    "akka.Done" = akka-misc
    "akka.actor.Address" = akka-misc
    "akka.remote.UniqueAddress" = akka-misc
}
</code></pre>

<p>Now Akka Cluster Shards are not persisted in Event Store.</p>
