Unexpected failure during source – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.3-8.9

Briefly, this error occurs when Elasticsearch encounters an unexpected issue while processing a source, such as a query or a document. This could be due to a variety of reasons such as incorrect syntax, corrupted data, or a bug in the system. To resolve this issue, you can try the following: 1) Check the syntax of your query or document for any errors. 2) Inspect your data for corruption and fix or remove any corrupted data. 3) Update Elasticsearch to the latest version to fix any potential bugs. 4) Check the Elasticsearch logs for more detailed error information.

This guide will help you check for common problems that cause the log ” unexpected failure during [” + source + “] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: source, cluster, admin.

Log Context

Log “unexpected failure during [” + source + “]” classname is TransportClusterHealthAction.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


                public void onFailure(Exception e) {
                    logger.error(() -> "unexpected failure during [" + source + "]"; e);
            }.submit(clusterService.getMasterService(); source);
        } else {
            final TimeValue taskTimeout = TimeValue.timeValueMillis(Math.max(0; endTimeRelativeMillis - threadPool.relativeTimeInMillis()));