karatelabs/karate · error

Invalid literal — expected 'false'

Error message

Invalid literal — expected 'false'

What it means

JsonParser.parseBoolean saw a token that is not the exact literal 'false' (and did not start with 't'). Any casing or spelling deviation — 'False', 'FALSE', 'fals', 'no' — is rejected because JSON defines booleans strictly.

Solutions

1. Replace the literal with lowercase 'false'.
2. Regenerate the payload with a real JSON serializer so booleans are encoded correctly.
3. Pre-normalize boolean-ish strings ('no', 'off', 'FALSE') to JSON booleans when converting other formats.
4. Check for truncation if the literal looks like a prefix of 'false'.

Example fix

// before
String json = "{\"debug\": FALSE}";
// after
String json = "{\"debug\": false}";

// normalize non-JSON booleans before parsing
raw = raw.replaceAll("\\bFalse\\b", "false")
         .replaceAll("\\bFALSE\\b", "false")
         .replaceAll("\\b(no|off)\\b(?=\\s*[:,}\\]])", "false");

// Java
try {
    Json json = Json.of(raw);
} catch (Exception e) {
    if (String.valueOf(e.getMessage()).contains("expected 'false'")) {
        raw = raw.replaceAll("\\b(False|FALSE|no|off)\\b", "false");
    } else { throw e; }
}

When it happens

Trigger: Parsing JSON containing 'False' (Python), 'FALSE' (SQL/CSV exports), 'no'/'off' (YAML-style booleans), or truncated text like '{"ok": fals}' in a value position dispatching to parseBoolean.

Common situations: YAML-to-JSON conversions where unquoted 'no' became an invalid literal; Python json dumps of raw bools via str(); hand-edited files with capitalized booleans; truncated payloads.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Related errors

• Invalid literal — expected 'true'
• Expected ':' after object key
• Expected string key in object
• Invalid literal — expected 'null'
• Invalid number

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/6af3aace359ab034. Report an issue: GitHub.

Appendix: source

Thrown at karate-js/src/main/java/io/karatelabs/js/JsonParser.java:335

                return v;
            } catch (NumberFormatException nfe) {
                return new BigInteger(lit);
            }
        }

        private Boolean parseBoolean() {
            if (s.charAt(pos) == 't') {
                if (pos + 4 <= len && s.charAt(pos + 1) == 'r' && s.charAt(pos + 2) == 'u' && s.charAt(pos + 3) == 'e') {
                    pos += 4;
                    return Boolean.TRUE;
                }
                throw syntaxError("Invalid literal — expected 'true'");
            }
            if (pos + 5 <= len && s.charAt(pos + 1) == 'a' && s.charAt(pos + 2) == 'l' && s.charAt(pos + 3) == 's' && s.charAt(pos + 4) == 'e') {
                pos += 5;
                return Boolean.FALSE;
            }
            throw syntaxError("Invalid literal — expected 'false'");
        }

        private Object parseNull() {
            if (pos + 4 <= len && s.charAt(pos + 1) == 'u' && s.charAt(pos + 2) == 'l' && s.charAt(pos + 3) == 'l') {
                pos += 4;
                return null;
            }
            throw syntaxError("Invalid literal — expected 'null'");
        }

        void skipWs() {
            while (pos < len) {
                char c = s.charAt(pos);
                if (c == ' ' || c == '\t' || c == '\n' || c == '\r') {
                    pos++;
                } else {
                    return;
                }

View on GitHub (pinned to a22eb90246)