ConcreteSetting getKey is malformed proxyBasePath – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Briefly, this error occurs when the Elasticsearch setting key is not correctly formatted or contains invalid characters. This could be due to a typo, incorrect syntax, or unsupported characters in the setting key. To resolve this issue, you should first verify the setting key for any typos or syntax errors. If the problem persists, check the Elasticsearch documentation for the correct format and supported characters for setting keys. Also, ensure that the proxy base path is correctly configured.

This guide will help you check for common problems that cause the log ” [” + concreteSetting.getKey() + “] is malformed [” + proxyBasePath + “] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “[” + concreteSetting.getKey() + “] is malformed [” + proxyBasePath + “]” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 // allow the user to configure proxies
 if (Strings.isNullOrEmpty(proxyBasePath) == false) {
 try {
 } catch (final IllegalArgumentException e) {
 throw new SettingsException("[" + concreteSetting.getKey() + "] is malformed [" + proxyBasePath + "]"; e);
 }  // allow the user to configure headers that go along with _every_ request
 configureHeaders(builder; config);