elastic/elasticsearch · error · IllegalArgumentException

[format] must not be null: [{name}]

Error message

[format] must not be null: [{name}]

What it means

Error "[format] must not be null: [{name}]" thrown in elastic/elasticsearch.

Source

Thrown at modules/aggregations/src/main/java/org/elasticsearch/aggregations/metric/ArrayValuesSourceAggregationBuilder.java:149

        }
        this.fields = fieldsArg;
        return (AB) this;
    }

    /**
     * Gets the field to use for this aggregation.
     */
    public List<String> fields() {
        return fields;
    }

    /**
     * Sets the format to use for the output of the aggregation.
     */
    @SuppressWarnings("unchecked")
    public AB format(String formatArg) {
        if (formatArg == null) {
            throw new IllegalArgumentException("[format] must not be null: [" + name + "]");
        }
        this.format = formatArg;
        return (AB) this;
    }

    /**
     * Gets the format to use for the output of the aggregation.
     */
    public String format() {
        return format;
    }

    /**
     * Sets the value to use when the aggregation finds a missing value in a
     * document
     */
    @SuppressWarnings("unchecked")
    public AB missingMap(Map<String, Object> missingMapArg) {

View on GitHub (pinned to db6a809a66)

When it happens

Trigger: Thrown at modules/aggregations/src/main/java/org/elasticsearch/aggregations/metric/ArrayValuesSourceAggregationBuilder.java:149 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/d78e719f1121ea66. Report an issue: GitHub.