apache/cassandra · error · java.lang.IllegalArgumentException

Unknown sstable format

Error message

Unknown sstable format: %s

What it means

DatabaseDescriptor.setSelectedSSTableFormat(String) looks up the named format in the registered sstable format table and throws IllegalArgumentException when no format with that name exists. SSTable formats must be registered before they can be selected.

Solutions

1. Use a registered format name exactly as returned by DatabaseDescriptor.getSSTableFormats() (e.g. via the SSTableFormat instance overload).
2. Register/verify the custom format implementation is loaded before selection.
3. Check spelling and case of the format name.

Example fix

// before
DatabaseDescriptor.setSelectedSSTableFormat("BIG"); // not registered by that name
// after
DatabaseDescriptor.setSelectedSSTableFormat("bti");

if (DatabaseDescriptor.getSSTableFormats().containsKey(name)) DatabaseDescriptor.setSelectedSSTableFormat(name);

boolean isKnownSSTableFormat(String name) { return DatabaseDescriptor.getSSTableFormats().containsKey(name); }

try { DatabaseDescriptor.setSelectedSSTableFormat(name); } catch (IllegalArgumentException e) { log.error("unknown sstable format: " + name, e); }

When it happens

Trigger: Calling setSelectedSSTableFormat("big") or any name not present in getSSTableFormats(); typically via @VisibleForTesting paths or config that specifies an sstable_format name that is not registered.

Common situations: Typos in the format name (case-sensitive lookup); attempting to select a pluggable format whose jar is not on the classpath/registered; tests referencing format names from a different Cassandra version.

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

• Cannot create CompressionParams for stored parameters
• Component is not present in the manifest
• Configuration contains options of unknown sstable formats
• denylist_max_keys_per_table must be a positive integer.
• denylist_max_keys_total must be a positive integer.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/6dd80e5fe56b97a9. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/config/DatabaseDescriptor.java:6162

        applySSTableFormats(factories, config);
    }

    public static ImmutableMap<String, SSTableFormat<?, ?>> getSSTableFormats()
    {
        return Objects.requireNonNull(sstableFormats, "Forgot to initialize DatabaseDescriptor?");
    }

    public static SSTableFormat<?, ?> getSelectedSSTableFormat()
    {
        return Objects.requireNonNull(selectedSSTableFormat, "Forgot to initialize DatabaseDescriptor?");
    }

    @VisibleForTesting
    public static void setSelectedSSTableFormat(String name)
    {
        SSTableFormat<?, ?> format = getSSTableFormats().get(name);
        if (format == null)
            throw new IllegalArgumentException("Unknown sstable format: " + name);
        setSelectedSSTableFormat(format);
    }

    @VisibleForTesting
    public static void setSelectedSSTableFormat(SSTableFormat<?, ?> format)
    {
        selectedSSTableFormat = Objects.requireNonNull(format);
    }

    public static boolean getDynamicDataMaskingEnabled()
    {
        return conf.dynamic_data_masking_enabled;
    }

    public static void setDynamicDataMaskingEnabled(boolean enabled)
    {
        if (enabled != conf.dynamic_data_masking_enabled)
        {

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