elastic/elasticsearch · error · IllegalArgumentException

field [{}] is null, cannot process it.

Error message

field [{}] is null, cannot process it.

What it means

Thrown by DissectProcessor.execute when the configured source field is null or absent and 'ignore_missing' is false (default). Same null-handling pattern as Convert/Csv processors: getFieldValue with ignoreMissing, and a null result without ignore_missing is fatal. The dissect pattern (key/value extraction) cannot run on null input.

Source

Thrown at modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DissectProcessor.java:46

    final String appendSeparator;
    final DissectParser dissectParser;

    DissectProcessor(String tag, String description, String field, String pattern, String appendSeparator, boolean ignoreMissing) {
        super(tag, description);
        this.field = field;
        this.ignoreMissing = ignoreMissing;
        this.pattern = pattern;
        this.appendSeparator = appendSeparator;
        this.dissectParser = new DissectParser(pattern, appendSeparator);
    }

    @Override
    public IngestDocument execute(IngestDocument ingestDocument) {
        String input = ingestDocument.getFieldValue(field, String.class, ignoreMissing);
        if (input == null && ignoreMissing) {
            return ingestDocument;
        } else if (input == null) {
            throw new IllegalArgumentException("field [" + field + "] is null, cannot process it.");
        }
        dissectParser.forceParse(input).forEach(ingestDocument::setFieldValue);
        return ingestDocument;
    }

    @Override
    public String getType() {
        return TYPE;
    }

    public static final class Factory implements Processor.Factory {

        @Override
        public DissectProcessor create(
            Map<String, Processor.Factory> registry,
            String processorTag,
            String description,
            Map<String, Object> config,

View on GitHub (pinned to db6a809a66)

Solutions

1. Set 'ignore_missing: true' on the dissect processor.
2. Confirm the 'field' name matches what prior processors or the source produce.
3. Set a default with a 'set' processor before dissect if absence should produce a default parsed shape.

Example fix

// before
{"dissect": {"field": "message", "patterns": ["%{ts} %{level} %{} %{msg}"]}}
// after
{"dissect": {"field": "message", "patterns": ["%{ts} %{level} %{} %{msg}"], "ignore_missing": true}}

// Default ignore_missing on dissect for optional fields.
{"dissect": {"field": "message", "patterns": ["%{ts} %{msg}"], "ignore_missing": true}}

{"on_failure": [{"index": {"index": "ingest-dlq"}}]}

When it happens

Trigger: A dissect processor whose 'field' is null or missing in the document, with ignore_missing omitted or false. The dissect pattern is never applied.

Common situations: Optional log fields; field renamed upstream; pipelines shared across heterogeneous log streams where only some have the dissected field; producers that emit null for empty values.

Related errors

• Field [{}] is null, cannot be converted to type [{}]
• field [{}] is null, cannot process it.
• missing field [{}] when calculating fingerprint
• field [{}] is null, cannot process it.
• Invalid language tag specified: {}

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/3b1527624c07161a. Report an issue: GitHub.