Reroute failed – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 7.11-8.9

Briefly, this error occurs when Elasticsearch is unable to allocate shards to nodes as per the cluster routing configuration. This could be due to insufficient resources, network issues, or incorrect configuration. To resolve this, you can try the following: 1) Check and adjust your cluster settings to ensure proper shard allocation. 2) Verify that all nodes are properly connected and network settings are correct. 3) Ensure that your nodes have sufficient resources (CPU, memory, disk space) to handle the shard allocation. 4) Check for any underlying hardware or software issues that might be causing the problem.

This guide will help you check for common problems that cause the log ” reroute failed ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, allocation.

Log Context

Log “reroute failed” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

            logger.trace("reroute succeeded after loading snapshot cache information");

        public void onFailure(Exception e) {
            logger.warn("reroute failed"; e);

    public static final String ALLOCATOR_NAME = "searchable_snapshot_allocator";