apache/cassandra · error · IllegalStateException

%s is expecting %d argument values. Getting %d instead.

Error message

%s is expecting %d argument values. Getting %d instead.

What it means

Before invoking a guardrail setter, the command validates that the number of provided value arguments equals the setter's parameter count; a mismatch throws IllegalStateException '<setter> is expecting <n> argument values. Getting <m> instead.'

Source

Thrown at src/java/org/apache/cassandra/tools/nodetool/GuardrailsConfigCommand.java:283

            if (parameterTypes.length == 1 && parameterTypes[0] == Set.class)
            {
                if (args.size() > 2)
                {
                    String guardrail = args.get(0);
                    // replace multiple arguments with one which is separated by a single comma
                    String collectedArguments = String.join(",", args.subList(1, args.size()));
                    args.clear();
                    args.add(guardrail);
                    args.add(collectedArguments);
                }
            }
        }

        private void validateArguments(Method setter, String setterName, List<String> args)
        {
            if (args.size() != setter.getParameterCount() + 1)
            {
                throw new IllegalStateException(format("%s is expecting %d argument values. Getting %d instead.",
                                                       setterName,
                                                       setter.getParameterCount(),
                                                       args.size() - 1));
            }
        }

        private Object[] prepareArguments(List<String> args, Method method)
        {
            Class<?>[] parameterTypes = method.getParameterTypes();
            Object[] arguments = new Object[args.size()];

            for (int i = 0; i < args.size(); i++)
                arguments[i] = castType(parameterTypes[i], args.get(i));

            if (method.getName().endsWith("Threshold"))
            {
                List<Object> thresholdArgs = Arrays.asList(arguments);
                Collections.reverse(thresholdArgs);

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Count the setter's expected parameters and supply exactly that many values after the guardrail name.
2. Check `nodetool help guardrails-config` or docs for the guardrail's arity.
3. For map/set guardrails, provide key and value pairs as separate arguments.

Example fix

// before
nodetool guardrailsconfig set partition_size_guardrail_warn 10MB
// after
nodetool guardrailsconfig set partition_size_guardrail_warn 10MB 100MB

ARITY = {'read_consistency_level': 1, 'partition_size_guardrail_warn': 2}
def validate_arity(name, values):
    expected = ARITY.get(name)
    if expected is not None and len(values) != expected:
        raise SystemExit(f'{name} expects {expected} value(s), got {len(values)}')

When it happens

Trigger: Running `nodetool guardrailsconfig set <name> v1 v2` for a single-parameter setter, or omitting values for a multi-parameter setter (e.g. map/two-threshold guardrails needing 2+ values).

Common situations: Two-parameter guardrails like minimum/maximum thresholds given only one value; accidentally pasting extra values; map-valued guardrails given one key without a value.

Related errors

• Do not specify additional arguments when --category/-c is se
• Guardrail %s not found.
• Unhandled return type:
• No arguments.
• Error occured when setting the config for setter %s with arg

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/8f7ba6265ea6da24. Report an issue: GitHub.