Failed to apply mappings – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-7.17

Briefly, this error occurs when Elasticsearch is unable to apply the defined mappings to an index. This could be due to incorrect mapping syntax, incompatible data types, or trying to change existing field types. To resolve this, ensure your mapping syntax is correct and data types match the data you’re indexing. If you’re modifying an existing index, remember that you can’t change the data type of an existing field. Instead, create a new index with the correct mappings and reindex your data.

In addition we recommend you run the Elasticsearch Template Optimizer to fix problems in your data modeling.

It will analyze your templates to detect issues and improve search performance, reduce indexing bottlenecks and optimize storage utilization. The Template Optimizer is free and requires no installation.

Log Context

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

            Mappings mappings = parseMappings(map; MergeReason.MAPPING_RECOVERY);
            assert assertRefreshIsNotNeeded(this.mapper; mappings);
            updatedEntries = applyMappings(mappings; () -> map.get(DEFAULT_MAPPING).string(); MergeReason.MAPPING_RECOVERY);
        } catch (Exception e) {
            logger.warn(() -> new ParameterizedMessage("[{}] failed to apply mappings"; index()); e);
            throw e;

        for (DocumentMapper documentMapper : updatedEntries.values()) {
            String mappingType = documentMapper.type();


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