apache/pulsar · error · RuntimeException

Invalid value '' for enum

Error message

Invalid value '' for enum 

What it means

Thrown by FieldParser.enum conversion when a string value cannot be resolved to a constant of the target enum type — Jackson's EnumResolver.findEnum returns null and the parser raises a RuntimeException naming both the invalid value and the enum type. This is used when mapping string configuration into typed fields.

Source

Thrown at pulsar-common/src/main/java/org/apache/pulsar/common/util/FieldParser.java:113

        // Lookup the suitable converter.
        String converterId = from.getClass().getName() + "_" + to.getName();
        Method converter = CONVERTERS.get(converterId);

        if (to.isEnum()) {
            // Converting string to enum
            DeserializationConfig deserializationConfig =
                    ObjectMapperFactory.getMapper().getObjectMapper().getDeserializationConfig();
            // No replacement API available in Jackson 2.x
            AnnotatedClass annotatedEnum = AnnotatedClassResolver.resolve(
                    deserializationConfig,
                    deserializationConfig.getTypeFactory().constructType(to),
                    deserializationConfig
            );
            EnumResolver r = EnumResolver.constructUsingToString(deserializationConfig, annotatedEnum);
            T value = (T) r.findEnum((String) from);
            if (value == null) {
                throw new RuntimeException("Invalid value '" + from + "' for enum " + to);
            }
            return value;
        }

        if (converter == null) {
            throw new UnsupportedOperationException("Cannot convert from " + from.getClass().getName() + " to "
                    + to.getName() + ". Requested converter does not exist.");
        }

        // Convert the value.
        try {
            Object val = converter.invoke(to, from);
            return to.cast(val);
        } catch (Exception e) {
            throw new RuntimeException("Cannot convert from " + from.getClass().getName() + " to " + to.getName()
                    + ". Conversion failed with " + e.getMessage(), e);
        }
    }

View on GitHub (pinned to 820761864e)

Solutions

1. Fix the configured value to exactly match an enum constant name (case-sensitive, no whitespace)
2. Check the enum's declared constants (e.g. print or read the target enum class) and pick a valid one
3. Align configuration with the Pulsar version in use — verify the constant exists in that release
4. Pre-validate the string with EnumUtils/Enum.valueOf inside a try-catch before assigning the config

Example fix

// before
FieldParser.value("CompressionTyppe.LZ4", CompressionType.class) // typo
// after
FieldParser.value("LZ4", CompressionType.class)

boolean valid = Arrays.stream(CompressionType.values())
    .anyMatch(e -> e.name().equals(cfgValue.trim()));
if (!valid) throw new IllegalArgumentException("invalid enum value: " + cfgValue);

static <E extends Enum<E>> boolean isValidEnumValue(String s, Class<E> type) {
    if (s == null) return false;
    return Arrays.stream(type.getEnumConstants()).anyMatch(e -> e.name().equals(s.trim()));
}

try {
    Object v = FieldParser.value(raw, CompressionType.class);
} catch (RuntimeException e) {
    log.error("Config value '{}' is not a valid {}; valid: {}", raw, "CompressionType",
        Arrays.toString(CompressionType.values()));
    throw e;
}

When it happens

Trigger: Calling FieldParser.value/convert (directly or via stringToList/stringToSet/stringToMap) with a string that is not an exact enum constant name of the target type — including wrong case, trailing whitespace, or a constant added only in newer Pulsar versions.

Common situations: Configuration files (broker/client/service_unit yaml) with a misspelled or mis-cased enum value; config copied from docs of a different Pulsar version where the enum constant changed; extra whitespace or quotes in the value; using display names instead of the enum constant name.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• --offloadedReadPriority parameter must be one of ${allowed}
• Malformed configuration file
• Unsupported token endpoint auth method: ${value}
• Invalid topic domain: '${value}'
• Unrecognized auto_failover_policy: ${policyType}

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/36018f34e8a715ae. Report an issue: GitHub.