Connection concurrently closed – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-7.4

Briefly, this error occurs when multiple connections to the Elasticsearch server are closed at the same time. This could be due to network issues, server overload, or improper configuration. To resolve this issue, you can try the following: 1) Check your network connection and ensure it’s stable. 2) Monitor your server’s performance to ensure it’s not overloaded. 3) Review your Elasticsearch configuration to ensure it’s set up correctly, particularly the settings related to connection handling. 4) If the issue persists, consider increasing the maximum number of allowed concurrent connections.

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

Log Context

Log “connection concurrently closed” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 connectedNodes.remove(node; finalConnection);
 if (conn.isClosed()) {
 throw new NodeNotConnectedException(node; "connection concurrently closed");
 success = true;
 listeners = connectingNodes.remove(node);
 } catch (ConnectTransportException e) {


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