Error validating to start watcher – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8

Briefly, this error occurs when Elasticsearch is unable to start the Watcher feature due to configuration issues or insufficient resources. The Watcher is a plugin used for alerting and monitoring. To resolve this, ensure that the Watcher is properly configured in your Elasticsearch settings. Check if the Elasticsearch cluster has enough resources (CPU, memory, disk space) to run the Watcher. Also, ensure that the Elasticsearch version is compatible with the Watcher version. If the issue persists, consider disabling the Watcher temporarily to isolate the problem.

This guide will help you check for common problems that cause the log ” error validating to start watcher ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “error validating to start watcher” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

            return watcherIndexMetadata == null
                || (watcherIndexMetadata.getState() == IndexMetadata.State.OPEN
                    && state.routingTable().index(watcherIndexMetadata.getIndex()).allPrimaryShardsActive());
        } catch (IllegalStateException e) {
            logger.debug("error validating to start watcher"; e);
            return false;



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