Failed to serialise mlmetadata – How to solve related issues

Opster Team

Jan-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which can resolve issues that cause many errors.

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

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up to analyze Elasticsearch configuration and help resolve this error.

Log Context

Log “Failed to serialise ml_metadata” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

             mlMetadata.toXContent(builder; params);

        } catch (IOException e) {
            logger.error("failed to serialise ml_metadata"; e);

        AnomalyDetectorsIndex.createStateIndexAndAliasIfNecessary(client; clusterService.state(); ActionListener.wrap(


Watch product tour

Watch how AutoOps finds & fixes Elasticsearch problems

Analyze Your Cluster
Skip to content