Failed to apply mappings – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch fails to apply the defined mappings to an index. This could be due to incorrect mapping syntax, incompatible data types, or attempting to change an existing field’s data type. To resolve this, ensure your mapping syntax is correct and data types match the data you’re indexing. If you’re modifying an existing field’s data type, consider creating a new field with the desired data type instead. Also, check for any underlying issues like insufficient cluster resources or network connectivity problems.

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This guide will help you check for common problems that cause the log ” [{}] failed to apply mappings ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: index.

Log Context

Log “[{}] failed to apply mappings” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

        final Map updatedEntries;
        try {
            // only update entries if needed
            updatedEntries = internalMerge(newIndexMetadata; MergeReason.MAPPING_RECOVERY);
        } catch (Exception e) {
            logger.warn(() -> new ParameterizedMessage("[{}] failed to apply mappings"; index()); e);
            throw e;

        boolean requireRefresh = false;


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