Scheduling reroute for delayed shards in delayed shards – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-7.15

Briefly, this error occurs when Elasticsearch has delayed the allocation of certain shards due to a node leaving the cluster. This could be due to network issues, hardware failure, or the node being overloaded. To resolve this issue, you can adjust the ‘delayed_timeout’ setting to a lower value to speed up the reallocation process. Alternatively, you can check the health of your nodes and network to prevent nodes from leaving the cluster unexpectedly. Lastly, ensure your cluster has enough resources to handle the workload and prevent nodes from being overloaded.

This guide will help you check for common problems that cause the log ” scheduling reroute for delayed shards in [{}] ({} delayed shards) ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster, routing, shards.

Log Context

Log “scheduling reroute for delayed shards in [{}] ({} delayed shards)” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

            } else {
                earlierRerouteNeeded = false;

            if (earlierRerouteNeeded) {
      "scheduling reroute for delayed shards in [{}] ({} delayed shards)"; nextDelay;
                DelayedRerouteTask currentTask = delayedRerouteTask.getAndSet(newTask);
                assert existingTask == currentTask || currentTask == null;
            } else {