Failure when trying to fetch existing cache sizes – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 7.11-8.9

Briefly, this error occurs when Elasticsearch is unable to retrieve the existing cache sizes due to issues like insufficient permissions, incorrect configuration, or network connectivity problems. To resolve this, you can check and adjust the user permissions, verify the Elasticsearch configuration settings, or troubleshoot the network connection. Additionally, ensure that the Elasticsearch cluster is running and accessible. If the problem persists, consider clearing the cache or increasing the cache size limit.

This guide will help you check for common problems that cause the log ” Failure when trying to fetch existing cache sizes ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, allocation, cache.

Log Context

Log “Failure when trying to fetch existing cache sizes” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


                    public void onFailure(Exception e) {
                        logger.warn("Failure when trying to fetch existing cache sizes"; e);
                        final Map res = Maps.newMapWithExpectedSize(dataNodes.length);
                        for (DiscoveryNode dataNode : dataNodes) {
                            res.put(dataNode; new NodeCacheFilesMetadata(dataNode; 0L));


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