apache/cassandra · error · ConfigurationException

compressor_providers entry is missing required 'class_name

Error message

compressor_providers entry is missing required 'class_name': %s

What it means

Each compressor_providers entry is a ParameterizedClass that must name the provider implementation via its class_name field. resolveProvider() throws ConfigurationException when class_name is null because there is nothing to instantiate. Without class_name Cassandra cannot know which AbstractCompressionProvider to construct for the given compressor key.

Solutions

1. Add the class_name field to the compressor_providers entry, e.g. 'LZ4: { class_name: com.example.MyCompressionProvider }'.
2. If you meant to use the built-in implementation, remove the entry entirely — absence of a provider falls back to DefaultCompressionProvider.
3. Validate that the config parser maps your YAML key to the expected class_name field (ParameterizedClass expects class_name, not class or className).

Example fix

// before
cassandra.yaml: compressor_providers: { LZ4: { } }
// after
cassandra.yaml: compressor_providers: { LZ4: { class_name: com.example.MyCompressionProvider } }

if (cfg.compressorProviders != null)
    for (Map.Entry<String, ParameterizedClass> e : cfg.compressorProviders.entrySet())
        if (e.getValue() == null || e.getValue().class_name == null)
            throw new IllegalArgumentException("compressor_providers entry for '" + e.getKey() + "' missing class_name");

boolean hasClassName(ParameterizedClass pc) { return pc != null && pc.class_name != null && !pc.class_name.trim().isEmpty(); }

try {
    registry.registerProviders(providers);
} catch (ConfigurationException e) {
    if (e.getMessage().contains("missing required 'class_name'")) log.error("Add class_name to compressor_providers entry");
    throw e;
}

When it happens

Trigger: registerProviders() resolving a provider config whose ParameterizedClass.class_name is null — e.g. a YAML entry like 'LZ4:' with an empty value, or a programmatically constructed ParameterizedClass without class_name set.

Common situations: YAML map entries where the value is omitted or left blank; refactoring code that builds ParameterizedClass objects and forgets to set class_name; copying config examples that use a different field name.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

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• commitlog_disk_access_mode =
• compressed_read_ahead_buffer_size_in_kb must be at least…
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• <ConfigurationException message>

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/7a73e05249c15730. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/io/compress/CompressorRegistry.java:273

        if (parameterizedClass == null)
            parameterizedClass = providerOptions.get(type.abbreviation);

        return parameterizedClass;
    }

    /**
     * Returns a compression provider with configuration specified in the config file.
     * If the provider fails to initialize or is not healthy, will attempt to fall back to the default provider
     * if enabled in the configuration.
     *
     * @param providerConfig the configuration for the provider
     * @return the compression provider instance
     * @throws ConfigurationException if both the specified and fallback providers fail to initialize
     */
    AbstractCompressionProvider resolveProvider(ParameterizedClass providerConfig)
    {
        if (providerConfig.class_name == null)
            throw new ConfigurationException("compressor_providers entry is missing required 'class_name': " + providerConfig);

        Map<String, String> p = providerConfig.parameters == null ? Collections.emptyMap() : providerConfig.parameters;

        try
        {
            AbstractCompressionProvider compressionProvider = FBUtilities.newCompressionProvider(providerConfig.class_name);
            compressionProvider.init(new HashMap<>(p));

            if (compressionProvider.isHealthy())
            {
                return compressionProvider;
            }
            else
            {
                logger.warn("Compression provider {} is not healthy, attempting fallback.", providerConfig.class_name);
            }
        }
        catch (Throwable e)

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