nathanmarz/storm · error · IllegalArgumentException

Don't know how to convert

Error message

Don't know how to convert ${o} + to int

What it means

Utils.getInt converts a config value object (typically from a Conf map) into an int. It only supports Long, Integer, and Short; any other type (e.g. String, Double) causes an IllegalArgumentException. It exists because Thrift/JSON config values deserializing from YAML often arrive as Long.

Solutions

1. Quote-free the value in the config: remove surrounding quotes so it parses as a number, then restart.
2. Convert before calling: Utils.getInt(Long.valueOf(o.toString())) or Integer.parseInt(o.toString()) if the value is a numeric String.
3. Pass an Integer/Long/Short object (cast or re-set the config value with the correct type).
4. For null, ensure the config key is actually set before reading.

Example fix

// before
int maxPending = Utils.getInt(conf.get("topology.max.spout.pending")); // value is String "20"
// after
Object v = conf.get("topology.max.spout.pending");
int maxPending = (v instanceof Number) ? Utils.getInt(v) : Integer.parseInt(String.valueOf(v));

Object v = conf.get(key);
if (!(v instanceof Long || v instanceof Integer || v instanceof Short)) {
    throw new IllegalArgumentException(key + " must be numeric, got: " + (v == null ? "null" : v.getClass().getName()));
}

boolean isIntLike(Object o) {
    return o instanceof Long || o instanceof Integer || o instanceof Short;
}

try {
    int value = Utils.getInt(o);
} catch (IllegalArgumentException e) {
    int value = Integer.parseInt(String.valueOf(o)); // handle numeric strings
}

When it happens

Trigger: Calling Utils.getInt(o) with a String (e.g. "10" loaded from an untyped config file), a Double, or a null; passing a config key whose value was set programmatically as a non-integral type into an API that calls getInt internally.

Common situations: YAML/JSON config files where a numeric setting was quoted ("topology.max.spout.pending: "20""), making it a String at runtime; configs set via a generic Map<String,Object> API with wrong value types.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Could not instantiate a class listed in config under section
• Unable to create serializer
• Cannot set serializations for a component using fluent API
• Could not find component with id
• Version already exists or data already exists

AI-assisted analysis of nathanmarz/storm@cdb116e942 (2026-09-12). Data as JSON: /api/errors/c490dd5ef5ff260d. Report an issue: GitHub.

Appendix: source

Thrown at storm-core/src/jvm/backtype/storm/utils/Utils.java:296

        }
        if(topology.get_bolts().containsKey(id)) {
            return topology.get_bolts().get(id).get_common();
        }
        if(topology.get_state_spouts().containsKey(id)) {
            return topology.get_state_spouts().get(id).get_common();
        }
        throw new IllegalArgumentException("Could not find component with id " + id);
    }
    
    public static Integer getInt(Object o) {
        if(o instanceof Long) {
            return ((Long) o ).intValue();
        } else if (o instanceof Integer) {
            return (Integer) o;
        } else if (o instanceof Short) {
            return ((Short) o).intValue();
        } else {
            throw new IllegalArgumentException("Don't know how to convert " + o + " + to int");
        }
    }
    
    public static long secureRandomLong() {
        return UUID.randomUUID().getLeastSignificantBits();
    }
    
    
    public static CuratorFramework newCurator(Map conf, List<String> servers, Object port, String root) {
        return newCurator(conf, servers, port, root, null);
    }

    public static class BoundedExponentialBackoffRetry extends ExponentialBackoffRetry {

        protected final int maxRetryInterval;

        public BoundedExponentialBackoffRetry(int baseSleepTimeMs, 
                int maxRetries, int maxSleepTimeMs) {

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