apache/cassandra · critical · ConfigurationException

Invalid yaml

Error message

Invalid yaml: <url>

What it means

YamlConfigurationLoader wraps any SnakeYAML exception raised while parsing/constructing the cassandra.yaml file into a ConfigurationException with this message. It means the YAML document at the given URL could not be parsed or mapped, and the original YAMLException is attached as the cause. Cassandra refuses to start with an unparsable config because configuration drives node behavior.

Solutions

1. Open the cause of the ConfigurationException (getCause()) to find the exact YAML parse error and line number
2. Validate the file with a YAML linter (e.g. python -c "import yaml,sys; yaml.safe_load(open('cassandra.yaml'))") before starting
3. Fix indentation: use spaces only, never tabs, and keep consistent 2-4 space levels
4. Ensure the URL points to a readable, complete cassandra.yaml

Example fix

// before (broken yaml)
commitlog_sync: periodic
  commitlog_sync_period_in_ms: 10000
// after
commitlog_sync: periodic
commitlog_sync_period_in_ms: 10000

import org.yaml.snakeyaml.Yaml;
try (var in = java.nio.file.Files.newInputStream(path)) {
    new Yaml().load(in); // throws before Cassandra does
}

try {
    config = loader.loadConfig(url);
} catch (ConfigurationException e) {
    log.error("Bad cassandra.yaml at " + url + ": " + e.getCause(), e);
    throw e;
}

When it happens

Trigger: Calling YamlConfigurationLoader.loadConfig(URL) (directly or via the 'config' loader factory) when the file contains YAML syntax errors (bad indentation, tabs, unclosed quotes) or content that cannot be deserialized; also triggered when loadConfig(byte[]) conversion of the bytes to a document fails inside loadConfig's try block.

Common situations: Hand-edited cassandra.yaml with a tab character or wrong indentation; truncated config after a failed deployment or volume mount; storing secrets in YAML that breaks quoting; copy-pasting config from a web page losing spacing.

Related errors

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• Cannot replace a live node...
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AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/148dd828fed3dbfd. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/config/YamlConfigurationLoader.java:166

        try
        {
            logger.debug("Loading settings from {}", url);
            byte[] configBytes;
            try (InputStream is = url.openStream())
            {
                configBytes = ByteStreams.toByteArray(is);
            }
            catch (IOException e)
            {
                // getStorageConfigURL should have ruled this out
                throw new AssertionError(e);
            }

            return loadConfig(configBytes);
        }
        catch (YAMLException e)
        {
            throw new ConfigurationException("Invalid yaml: " + url, e);
        }
    }

    @VisibleForTesting
    static Config loadConfig(byte[] configBytes)
    {
        SafeConstructor constructor = new CustomConstructor(Config.class, Yaml.class.getClassLoader());
        Map<Class<?>, Map<String, Replacement>> replacements = getNameReplacements(Config.class);
        verifyReplacements(replacements, configBytes);
        PropertiesChecker propertiesChecker = new PropertiesChecker(replacements);
        constructor.setPropertyUtils(propertiesChecker);
        Yaml yaml = new Yaml(constructor);
        Config result = loadConfig(yaml, configBytes);
        propertiesChecker.check();
        maybeAddEnvironmentVariables(result);
        maybeAddSystemProperties(result);
        return result;
    }

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