elastic/elasticsearch · error · IllegalArgumentException

unable to convert [{}] to double

Error message

unable to convert [{}] to double

What it means

ConvertProcessor.Type.DOUBLE.convert wraps NumberFormatException from Double.parseDouble on value.toString(). Double.parseDouble is stricter than many users expect: it rejects trailing characters, leading/trailing whitespace, and locale-specific separators. The offending value is interpolated into the message.

Source

Thrown at modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/ConvertProcessor.java:68

            public Object convert(Object value) {
                try {
                    String strValue = value.toString();
                    if (strValue.startsWith("0x") || strValue.startsWith("-0x")) {
                        return Long.decode(strValue);
                    }
                    return Long.parseLong(strValue);
                } catch (NumberFormatException e) {
                    throw new IllegalArgumentException("unable to convert [" + value + "] to long", e);
                }
            }
        },
        DOUBLE {
            @Override
            public Object convert(Object value) {
                try {
                    return Double.parseDouble(value.toString());
                } catch (NumberFormatException e) {
                    throw new IllegalArgumentException("unable to convert [" + value + "] to double", e);
                }
            }
        },
        FLOAT {
            @Override
            public Object convert(Object value) {
                try {
                    return Float.parseFloat(value.toString());
                } catch (NumberFormatException e) {
                    throw new IllegalArgumentException("unable to convert [" + value + "] to float", e);
                }
            }
        },
        BOOLEAN {
            @Override
            public Object convert(Object value) {
                if (value.toString().equalsIgnoreCase("true")) {
                    return true;

View on GitHub (pinned to db6a809a66)

Solutions

1. Strip whitespace, currency symbols, and unit suffixes from the value before convert.
2. Replace locale decimal separators (',') with '.' upstream if applicable.
3. Set ignore_missing: true for absent fields; filter empty strings upstream.
4. Quarantine unparseable values via on_failure.

Example fix

// before — comma decimal separator fails Double.parseDouble
//   { "convert": { "field": "temp", "type": "double" } }  // temp = "36,6"
//
// after — normalize the separator first
//   { "script": { "source": "ctx.temp = ctx.temp.replace(',', '.')" } },
//   { "convert": { "field": "temp", "type": "double" } }

boolean isParsableAsDouble(Object v) {
    if (v == null) return false;
    String s = v.toString().trim();
    try { Double.parseDouble(s); return true; } catch (NumberFormatException ignored) { return false; }
}

static boolean isDoubleLike(Object v) {
    if (v instanceof Number) return true;
    if (v instanceof String s) {
        try { Double.parseDouble(s.trim()); return true; } catch (NumberFormatException ignored) { return false; }
    }
    return false;
}

{
  "convert": {
    "field": "temp", "type": "double",
    "on_failure": [
      { "set": { "field": "ingest.error", "value": "convert-double" } },
      { "redirect": { "pipeline": "quarantine" } }
    ]
  }
}

When it happens

Trigger: convert processor with type: double on a value like '1,5' (comma decimal separator), '12 USD', 'abc', 'NaN-text', or with leading/trailing whitespace. Multi-valued fields fail on the first unparseable element.

Common situations: Non-English locales that use ',' as decimal separator; currency strings; values with units ('3.14m'); values with surrounding whitespace that survived sanitization.

Related errors

• unable to convert [{}] to integer
• unable to convert [{}] to long
• unable to parse URI [${uriString}]
• Illegal escape sequence '\{}'
• Invalid extensions in the CEF event: {}

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/35c8e51d970d3530. Report an issue: GitHub.