apache/pulsar · error · IllegalArgumentException

Field '${name}' cannot be null!

Error message

Field '${name}' cannot be null!

What it means

ValidatorImpls.NotNullValidator.validateField throws IllegalArgumentException when the validated value is null. It is the simplest validator: any non-null object passes, null is rejected with a message naming the field.

Source

Thrown at pulsar-config-validation/src/main/java/org/apache/pulsar/config/validation/ValidatorImpls.java:80

            throw new IllegalArgumentException(String.format("Field '%s' must be a Positive Number", name));
        }

        @Override
        public void validateField(String name, Object o) {
            validateField(name, this.includeZero, o);
        }
    }

    /**
     * Validates if an object is not null.
     */

    public static class NotNullValidator extends Validator {

        @Override
        public void validateField(String name, Object o) {
            if (o == null) {
                throw new IllegalArgumentException(String.format("Field '%s' cannot be null!", name));
            }
        }
    }

    /**
     * Validates each entry in a list.
     */
    public static class ListEntryTypeValidator extends Validator {

        private Class<?> type;

        public ListEntryTypeValidator(Map<String, Object> params) {
            this.type = (Class<?>) params.get(ConfigValidationAnnotations.ValidatorParams.TYPE);
        }

        public static void validateField(String name, Class<?> type, Object o) {
            ConfigValidationUtils.NestableFieldValidator validator = ConfigValidationUtils.listFv(type, false);
            validator.validateField(name, o);

View on GitHub (pinned to 820761864e)

Solutions

1. Set the missing field in the configuration file or properties map before validation
2. Fix the key spelling so the intended value is actually picked up
3. Give the field a default value in the config class if it is genuinely optional, and remove the NotNullValidator in that case

Example fix

# before
# advertisedAddress missing
# after
advertisedAddress=broker-1.example.com

// before validateConfig
java.util.Set<String> notNullFields = java.util.Set.of("advertisedAddress", "clusterName");
for (String f : notNullFields) {
    if (conf.get(f) == null) throw new IllegalStateException("required field missing: " + f);
}

try {
    ConfigValidation.validateConfig(conf);
} catch (IllegalArgumentException e) {
    throw new IllegalStateException("Required config field is null: " + e.getMessage(), e);
}

When it happens

Trigger: A config field validated with NotNullValidator (via @NotNullValidator annotation or programmatic Validator use) left null because the property was missing from the supplied config map/properties at validateConfig time.

Common situations: A required setting omitted from broker.conf/standalone.conf or from a programmatically-built config object; YAML/properties key misspelled so it deserializes to null.

Related errors

• Field ${name} must not be null
• ERROR_DECODING_JWT
• ${pd}${name} must be a ${cls.getName()}. (${field})
• Field ${name} must be an Iterable but was a ${field.getClass
• Field ${name} must be a Map

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/06827a0d38574834. Report an issue: GitHub.