Opster Team
Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many errors.
To easily locate the root cause and resolve this issue try AutoOps for Elasticsearch & OpenSearch. It diagnoses problems by analyzing hundreds of metrics collected by a lightweight agent and offers guidance for resolving them.
This guide will help you check for common problems that cause the log ” Failed to notify listeners ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: listeners and snapshots.

Log Context
Log “Failed to notify listeners” classname is SnapshotsService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
ActionListener.onFailure(completionListeners; failure); } else { ActionListener.onResponse(completionListeners; snapshotInfo); } } catch (Exception e) { logger.warn("Failed to notify listeners"; e); } } endingSnapshots.remove(snapshot); if (listener != null) { listener.onResponse(snapshotInfo);
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Billy McCarthy
Senior SysAdmin at Backblaze