apache/cassandra · error · IllegalArgumentException

Unexpected parameter

Error message

Unexpected parameter '%s', must be one of %s

What it means

RepairTokenRangeSplitter.setParameter validates the key against the PARAMETERS set and throws IllegalArgumentException listing all accepted keys when the key is unknown. After validation it records the value and re-runs reinitParameters.

Solutions

1. Use only keys in the splitter's PARAMETERS set (bytes_per_assignment, max_bytes_per_schedule, ...)
2. Read the accepted list printed in the error message
3. Run nodetool getautorepairconfig to see current valid configuration
4. Fix spelling and re-apply the update

Example fix

// before
splitter.setParameter("bytes_per_assigment", "1GB");
// after
splitter.setParameter("bytes_per_assignment", "1GB");

Set<String> ALLOWED = Set.of("bytes_per_assignment","max_bytes_per_schedule");
if (!ALLOWED.contains(key))
    throw new IllegalArgumentException("Key " + key + " not in " + ALLOWED);

try { splitter.setParameter(key, value); }
catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("Unexpected parameter"))
        logger.warn("Unknown auto-repair param {}; accepted list: {}", key, e.getMessage());
    else throw e;
}

When it happens

Trigger: Dynamic auto-repair config update with a key not in PARAMETERS (e.g. typo like bytes_per_assigment, or a FixedSplit-only key such as number_of_subranges).

Common situations: Typos in nodetool setautorepairconfig or cassandra.yaml; copying keys between the two splitter implementations; older config keys removed after upgrade.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Unexpected parameter
• does not support custom configuration
• =' ' cannot be greater than =' ' for
• Unable to create instance of IAutoRepairTokenRangeSplitter
• a hints file cannot be configured for both compression and…

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/f84fd64399dd954c. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/repair/autorepair/RepairTokenRangeSplitter.java:625

            Iterable<SSTableReader> sstables = cfs.getTracker().getView().select(SSTableSet.CANONICAL);
            SSTableIntervalTree tree = SSTableIntervalTree.buildSSTableIntervalTree(ImmutableList.copyOf(sstables));
            Range<PartitionPosition> r = Range.makeRowRange(tokenRange);
            List<SSTableReader> canonicalSSTables = View.sstablesInBounds(r.left, r.right, tree);
            if (repairType == AutoRepairConfig.RepairType.INCREMENTAL)
            {
                canonicalSSTables = canonicalSSTables.stream().filter((sstable) -> !sstable.isRepaired()).collect(Collectors.toList());
            }
            refs = Refs.tryRef(canonicalSSTables);
        }
        return refs;
    }

    @Override
    public void setParameter(String key, String value)
    {
        if (!PARAMETERS.contains(key))
        {
            throw new IllegalArgumentException("Unexpected parameter '" + key + "', must be one of " + PARAMETERS);
        }

        logger.info("Setting {} to {} for repair type {}", key, value, repairType);
        givenParameters.put(key, value);
        reinitParameters();
    }

    @Override
    public Map<String, String> getParameters()
    {
        final Map<String, String> parameters = new LinkedHashMap<>();
        for (String parameter : PARAMETERS)
        {
            // Use the parameter as provided if present.
            if (givenParameters.containsKey(parameter))
            {
                parameters.put(parameter, givenParameters.get(parameter));
                continue;

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