apache/maven · error · IllegalArgumentException

not function requires exactly one argument

Error message

not function requires exactly one argument

What it means

not() is a built-in function of Maven 4.1 profile activation conditions (<activation><condition>). ConditionFunctions.not throws IllegalArgumentException unless exactly one boolean argument is supplied; the activator records 'Error parsing profile activation condition' and the profile remains inactive.

Source

Thrown at impl/maven-impl/src/main/java/org/apache/maven/impl/model/profile/ConditionFunctions.java:170

    public Object matches(List<Object> args) {
        if (args.size() != 2) {
            throw new IllegalArgumentException("matches function requires exactly two arguments");
        }
        String s = ConditionParser.toString(args.get(0));
        String regex = ConditionParser.toString(args.get(1));
        return s.matches(regex);
    }

    /**
     * Negates a boolean value.
     *
     * @param args A list containing a single boolean argument
     * @return The negation of the input boolean
     * @throws IllegalArgumentException if the number of arguments is not exactly one
     */
    public Object not(List<Object> args) {
        if (args.size() != 1) {
            throw new IllegalArgumentException("not function requires exactly one argument");
        }
        return !ConditionParser.toBoolean(args.get(0));
    }

    /**
     * Implements an if-then-else operation.
     *
     * @param args A list containing three arguments: condition, value if true, value if false
     * @return The second argument if the condition is true, the third argument otherwise
     * @throws IllegalArgumentException if the number of arguments is not exactly three
     */
    @SuppressWarnings("checkstyle:MethodName")
    public Object if_(List<Object> args) {
        if (args.size() != 3) {
            throw new IllegalArgumentException("if function requires exactly three arguments");
        }
        boolean condition = ConditionParser.toBoolean(args.get(0));
        return condition ? args.get(1) : args.get(2);

View on GitHub (pinned to e4093d4e12)

Solutions

1. Wrap exactly one boolean expression: not(exists('src/main/groovy'))
2. For multiple conditions use operators, e.g. not(exists('a')) and not(exists('b'))
3. Verify with mvn help:active-profiles after the fix

Example fix

<!-- before -->
<condition>not(exists('src/main/groovy'), exists('src/main/scala'))</condition>

<!-- after -->
<condition>not(exists('src/main/groovy')) and not(exists('src/main/scala'))</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, "not", 1, 1);

try {
    Object r = new ConditionParser(functions, resolver).parse(condition);
} catch (IllegalArgumentException e) {
    // report and treat the profile as inactive
}

When it happens

Trigger: A condition like not(exists('x'), exists('y')) with two arguments, or not() with none — the only valid form is not(<boolean expression>), e.g. not(exists('src/main/groovy')).

Common situations: Trying to negate two conditions in one call instead of using 'and'/'or' operators; an empty argument list left behind after deleting the inner expression.

Related errors

• length function requires exactly one argument
• upper function requires exactly one argument
• lower function requires exactly one argument
• substring function requires 2 or 3 arguments
• indexOf function requires exactly two arguments

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/3eec5920e16f1839. Report an issue: GitHub.