Failing shard with unassigned info – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.9

Briefly, this error occurs when a shard in Elasticsearch cannot be assigned to a node. This could be due to various reasons such as insufficient disk space, network connectivity issues, or a node failure. To resolve this issue, you can try to manually reroute the unassigned shard to a specific node using the cluster reroute API. Alternatively, you can also check the cluster health and ensure that all nodes are properly connected and have sufficient resources. If a node has failed, you may need to restart it or add a new node to the cluster.

This guide will help you check for common problems that cause the log ” {} failing shard {} with unassigned info ({}) ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: routing, cluster, shard.

Log Context

Log “{} failing shard {} with unassigned info ({})” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

            : "shard routing to fail does not exist in routing table; expected: "
                + failedShard
                + " but was: "
                + getByAllocationId(failedShard.shardId(); failedShard.allocationId().getId());

        logger.debug("{} failing shard {} with unassigned info ({})"; failedShard.shardId(); failedShard; unassignedInfo.shortSummary());

        // if this is a primary; fail initializing replicas first (otherwise we move RoutingNodes into an inconsistent state)
        if (failedShard.primary()) {
            List assignedShards = assignedShards(failedShard.shardId());
            if (assignedShards.isEmpty() == false) {


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