apache/cassandra · error · IllegalArgumentException

Unexpected parameter

Error message

Unexpected parameter '%s', must be %s

What it means

FixedSplitTokenRangeSplitter.setParameter rejects any parameter key other than the constant NUMBER_OF_SUBRANGES with an IllegalArgumentException. This splitter supports exactly one configurable option.

Solutions

1. Use only the 'number_of_subranges' key for FixedSplitTokenRangeSplitter
2. Switch to RepairTokenRangeSplitter if bytes-based parameters are needed
3. Correct the key spelling in the auto_repair config
4. Use nodetool getautorepairconfig to see current valid parameters

Example fix

// before
splitter.setParameter("bytes_per_assignment", "1GB");
// after
splitter.setParameter("number_of_subranges", "10");

if (!"number_of_subranges".equals(key))
    throw new IllegalArgumentException("FixedSplitTokenRangeSplitter only accepts number_of_subranges");

try { splitter.setParameter(key, value); }
catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("Unexpected parameter")) logger.warn("Invalid param {} for fixed splitter", key);
    else throw e;
}

When it happens

Trigger: Dynamically updating auto-repair config (nodetool setautorepairconfig / config reload) with a key the FixedSplit splitter doesn't recognize, e.g. bytes_per_assignment or a misspelled number_of_subranges.

Common situations: Copy-pasting bytes-based parameters intended for RepairTokenRangeSplitter onto FixedSplitTokenRangeSplitter; typos like number_of_subrange; stale config carrying obsolete keys.

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/99c2887e3d3ad25e. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/repair/autorepair/FixedSplitTokenRangeSplitter.java:142

            for (String tableName : tableNames)
            {
                long totalBytes = repairPlan.getTableEstimatedBytes(AutoRepairUtils.getKeyspaceTableName(keyspaceName, tableName));
                long bytesPerRange = Math.max(1, totalBytes / splitsPerRange);
                for (Range<Token> splitRange : allRanges)
                {
                    repairAssignments.add(new RepairAssignment(splitRange, keyspaceName, Collections.singletonList(tableName), bytesPerRange));
                }
            }
        }
        return new KeyspaceRepairAssignments(priority, keyspaceName, repairAssignments);
    }

    @Override
    public void setParameter(String key, String value)
    {
        if (!key.equals(NUMBER_OF_SUBRANGES))
        {
            throw new IllegalArgumentException("Unexpected parameter '" + key + "', must be " + NUMBER_OF_SUBRANGES);
        }
        logger.info("Setting {} to {} for repair type {}", key, value, repairType);
        this.numberOfSubranges = Integer.parseInt(value);
    }

    @Override
    public Map<String, String> getParameters()
    {
        return Collections.singletonMap(NUMBER_OF_SUBRANGES, Integer.toString(numberOfSubranges));
    }
}

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