elastic/elasticsearch · error · RuntimeException

Invalid escaped char in [{}]

Error message

Invalid escaped char in [{}]

What it means

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

Source

Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/MappingCharFilterFactory.java:76

                throw new RuntimeException("Invalid Mapping Rule : [" + rule + "]");
            }
            String lhs = parseString(m.group(1).trim());
            String rhs = parseString(m.group(2).trim());
            if (lhs == null || rhs == null) throw new RuntimeException("Invalid Mapping Rule : [" + rule + "]. Illegal mapping.");
            map.add(lhs, rhs);
        }
    }

    char[] out = new char[256];

    private String parseString(String s) {
        int readPos = 0;
        int len = s.length();
        int writePos = 0;
        while (readPos < len) {
            char c = s.charAt(readPos++);
            if (c == '\\') {
                if (readPos >= len) throw new RuntimeException("Invalid escaped char in [" + s + "]");
                c = s.charAt(readPos++);
                switch (c) {
                    case '\\' -> c = '\\';
                    case 'n' -> c = '\n';
                    case 't' -> c = '\t';
                    case 'r' -> c = '\r';
                    case 'b' -> c = '\b';
                    case 'f' -> c = '\f';
                    case 'u' -> {
                        if (readPos + 3 >= len) throw new RuntimeException("Invalid escaped char in [" + s + "]");
                        c = (char) Integer.parseInt(s.substring(readPos, readPos + 4), 16);
                        readPos += 4;
                    }
                }
            }
            out[writePos++] = c;
        }
        return new String(out, 0, writePos);

View on GitHub (pinned to db6a809a66)

When it happens

Trigger: Thrown at modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/MappingCharFilterFactory.java:76 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/7596025be47c7c92. Report an issue: GitHub.