apache/maven · error · IllegalArgumentException

substring function requires 2 or 3 arguments

Error message

substring function requires 2 or 3 arguments

What it means

substring() is a built-in function of Maven 4.1 profile activation conditions (<activation><condition>). ConditionFunctions.substring accepts exactly two or three arguments (string, start, optional end) and throws IllegalArgumentException for any other count; the activator records 'Error parsing profile activation condition' and leaves the profile inactive.

Source

Thrown at impl/maven-impl/src/main/java/org/apache/maven/impl/model/profile/ConditionFunctions.java:105

     */
    public Object lower(List<Object> args) {
        if (args.size() != 1) {
            throw new IllegalArgumentException("lower function requires exactly one argument");
        }
        String s = ConditionParser.toString(args.get(0));
        return s.toLowerCase();
    }

    /**
     * Returns a substring of the given string.
     *
     * @param args A list containing 2 or 3 arguments: the string, start index, and optionally end index
     * @return The substring
     * @throws IllegalArgumentException if the number of arguments is not 2 or 3
     */
    public Object substring(List<Object> args) {
        if (args.size() < 2 || args.size() > 3) {
            throw new IllegalArgumentException("substring function requires 2 or 3 arguments");
        }
        String s = ConditionParser.toString(args.get(0));
        int start = toInt(args.get(1));
        int end = args.size() == 3 ? toInt(args.get(2)) : s.length();
        return s.substring(start, end);
    }

    /**
     * Finds the index of a substring within a string.
     *
     * @param args A list containing two strings: the main string and the substring to find
     * @return The index of the substring, or -1 if not found
     * @throws IllegalArgumentException if the number of arguments is not exactly two
     */
    public Object indexOf(List<Object> args) {
        if (args.size() != 2) {
            throw new IllegalArgumentException("indexOf function requires exactly two arguments");
        }

View on GitHub (pinned to e4093d4e12)

Solutions

1. Supply two or three arguments, e.g. substring(${java.version}, 0, 2) == '17'
2. Remember the end index is optional and defaults to the string length, but the start index is mandatory
3. Verify with mvn help:active-profiles after the fix

Example fix

<!-- before -->
<condition>substring(${java.version}) == '17'</condition>

<!-- after -->
<condition>substring(${java.version}, 0, 2) == '17'</condition>

static boolean arityOk(String condition, String fn, int min, int max) {
    int i = condition.indexOf(fn + "(");
    if (i < 0) return true;
    String args = condition.substring(i + fn.length() + 1, condition.indexOf(')', i));
    int n = args.isBlank() ? 0 : args.split(",", -1).length;
    return n >= min && n <= max;
}
boolean ok = arityOk(condition, "substring", 2, 3);

try {
    Object r = new ConditionParser(functions, resolver).parse(condition);
} catch (IllegalArgumentException e) {
    // wrong arity (also possible: StringIndexOutOfBounds values arrive as parse errors)
}

When it happens

Trigger: A condition like substring(${java.version}) (one argument) or substring(${java.version}, 0, 2, 1) (four) — valid forms are substring(s, start) and substring(s, start, end).

Common situations: Expecting the string alone to be enough; carrying over an extra step/flags argument from another language's substring; forgetting the start index while extracting a prefix.

Related errors

• length function requires exactly one argument
• upper function requires exactly one argument
• lower function requires exactly one argument
• indexOf function requires exactly two arguments
• contains function requires exactly two arguments

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/9f6934040fcdc18e. Report an issue: GitHub.