json-path/JsonPath · error · InvalidPathException

Arguments to function: '' are not closed properly.

Error message

Arguments to function: '' are not closed properly.

What it means

When the compiler scans a function-call token `name(...)`, it tracks parenthesis nesting; if the closing parenthesis is never found before the path string ends, the arguments are considered unclosed and compilation throws InvalidPathException naming the function.

Source

Thrown at json-path/src/main/java/com/jayway/jsonpath/internal/path/PathCompiler.java:226

            endPosition = path.length();
        }


        List<Parameter> functionParameters = null;
        if (isFunction) {
            int parenthesis_count = 1;
            for(int i = readPosition + 1; i < path.length(); i++){
                if (path.charAt(i) == CLOSE_PARENTHESIS)
                    parenthesis_count--;
                else if (path.charAt(i) == OPEN_PARENTHESIS)
                    parenthesis_count++;
                if (parenthesis_count == 0)
                    break;
            }

            if (parenthesis_count != 0){
                String functionName = path.subSequence(startPosition, endPosition).toString();
                throw new InvalidPathException("Arguments to function: '" + functionName + "' are not closed properly.");
            }

            if (path.inBounds(readPosition+1)) {
                // read the next token to determine if we have a simple no-args function call
                char c = path.charAt(readPosition + 1);
                if (c != CLOSE_PARENTHESIS) {
                    path.setPosition(endPosition+1);
                    // parse the arguments of the function - arguments that are inner queries or JSON document(s)
                    String functionName = path.subSequence(startPosition, endPosition).toString();
                    functionParameters = parseFunctionParameters(functionName);
                } else {
                    path.setPosition(readPosition + 1);
                }
            }
            else {
                path.setPosition(readPosition);
            }
        }

View on GitHub (pinned to 62a4c9f0f6)

Solutions

1. Balance the parentheses in the path, e.g. `$.length(` → `$.length()`.
2. For filters with functions, ensure the whole predicate is closed: `$[?(@.x.length() > 2)]`.
3. When generating paths in code, count/verify parentheses before compiling, and log the full untruncated path on failure.

Example fix

// before
JsonPath.read(json, "$.items.length(");
// after
JsonPath.read(json, "$.items.length()");

boolean parensBalanced(String path) {
    int n = 0;
    for (char c : path.toCharArray()) {
        if (c == '(') n++;
        if (c == ')') n--;
        if (n < 0) return false;
    }
    return n == 0;
}

try {
    return JsonPath.read(json, path);
} catch (InvalidPathException e) {
    throw new IllegalArgumentException("Unclosed function arguments in path: " + path, e);
}

When it happens

Trigger: Paths with unbalanced parentheses such as `$.length()` written as `$.length(`, nested calls missing a close like `$.sum((@.x, @.y`, or truncation of a long path string.

Common situations: Hand-written function paths (length, min, max, avg, concat, etc.) with typos; string truncation in logs/configs; generated filter expressions where the closing paren was appended after a conditional that got skipped.

Related errors

• Function with name: does not exist.
• Failed to parse ArrayIndexOperation:
• Failed to parse token in ArrayIndexOperation:
• Path must start with '$' or '@'
• Path must not end with a '.

AI-assisted analysis of json-path/JsonPath@62a4c9f0f6 (2026-09-11). Data as JSON: /api/errors/7a7c61b95ce79eda. Report an issue: GitHub.