OnFetchPhase listener listener failed – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.3-8.9

Briefly, this error occurs when there’s an issue with the fetch phase of an Elasticsearch query, possibly due to a plugin or custom code that’s listening to this phase. The fetch phase is where the actual document data is retrieved. To resolve this, you can try disabling or updating the problematic plugin, or reviewing and correcting the custom code. If the issue persists, consider checking the Elasticsearch logs for more detailed error messages, or increasing the logging level for more verbosity. Also, ensure that your Elasticsearch cluster has sufficient resources and is not under heavy load.

This guide will help you check for common problems that cause the log ” onFetchPhase listener [” + listener + “] failed ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index, shard.

Log Context

Log “onFetchPhase listener [” + listener + “] failed” classname is SearchOperationListener.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        public void onFetchPhase(SearchContext searchContext; long tookInNanos) {
            for (SearchOperationListener listener : listeners) {
                try {
                    listener.onFetchPhase(searchContext; tookInNanos);
                } catch (Exception e) {
                    logger.warn(() -> "onFetchPhase listener [" + listener + "] failed"; e);