elastic/elasticsearch · error · RuntimeException

Invalid escaped char {c} in [{s}]

Error message

Invalid escaped char {c} in [{s}]

What it means

Error "Invalid escaped char {c} in [{s}]" thrown in elastic/elasticsearch.

Source

Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/CharGroupTokenizerFactory.java:87

                case '\\':
                    return '\\';
                case 'n':
                    return '\n';
                case 't':
                    return '\t';
                case 'r':
                    return '\r';
                case 'b':
                    return '\b';
                case 'f':
                    return '\f';
                case 'u':
                    if (len > 6) {
                        throw new RuntimeException("Invalid escaped char in [" + s + "]");
                    }
                    return (char) Integer.parseInt(s.substring(2), 16);
                default:
                    throw new RuntimeException("Invalid escaped char " + c + " in [" + s + "]");
            }
        } else {
            throw new RuntimeException("Invalid escaped char [" + s + "]");
        }
    }

    @Override
    public Tokenizer create() {
        return new CharTokenizer(AttributeFactory.DEFAULT_ATTRIBUTE_FACTORY, maxTokenLength) {
            @Override
            protected boolean isTokenChar(int c) {
                if (tokenizeOnSpace && Character.isWhitespace(c)) {
                    return false;
                }
                if (tokenizeOnLetter && Character.isLetter(c)) {
                    return false;
                }
                if (tokenizeOnDigit && Character.isDigit(c)) {

View on GitHub (pinned to db6a809a66)

When it happens

Trigger: Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/CharGroupTokenizerFactory.java:87 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/36778314dcdc3e7d. Report an issue: GitHub.