apache/cassandra · error · IllegalArgumentException

Concurrent accord operations must be non-negative

Error message

Concurrent accord operations must be non-negative

What it means

DatabaseDescriptor.setConcurrentAccordOps validates the number of concurrent Accord transactional operations before storing it in the config. Cassandra requires a non-negative thread/operation count for the Accord queue; a negative value is nonsense and is rejected with IllegalArgumentException immediately.

Source

Thrown at src/java/org/apache/cassandra/config/DatabaseDescriptor.java:2986

        }
        conf.concurrent_materialized_view_writes = concurrent_materialized_view_writes;
    }

    public static int getAccordConcurrentMigrationOps()
    {
        return conf.accord.migration_concurrency.or(2 * FBUtilities.getAvailableProcessors());
    }

    public static int getAccordConcurrentOps()
    {
        return conf.accord.queue_thread_count.or(2 * FBUtilities.getAvailableProcessors());
    }

    public static void setConcurrentAccordOps(int concurrent_operations)
    {
        if (concurrent_operations < 0)
        {
            throw new IllegalArgumentException("Concurrent accord operations must be non-negative");
        }
        conf.accord.queue_thread_count = new OptionaldPositiveInt(concurrent_operations);
    }

    public static void setConcurrentAccordMigrationOps(int concurrent_operations)
    {
        if (concurrent_operations < 0)
        {
            throw new IllegalArgumentException("Concurrent accord operations must be non-negative");
        }
        conf.accord.migration_concurrency = new OptionaldPositiveInt(concurrent_operations);
    }

    public static int getFlushWriters()
    {
        return conf.memtable_flush_writers;
    }

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Pass a value >= 0 (use 0 to let Cassandra use its default, since the field is an OptionaldPositiveInt).
2. Fix the upstream calculation or script that produced the negative number.
3. Clamp before calling: Math.max(0, concurrentOperations).

Example fix

// before
databaseDescriptor.setConcurrentAccordOps(baseCount - extraCount); // may be negative
// after
int ops = Math.max(0, baseCount - extraCount);
databaseDescriptor.setConcurrentAccordOps(ops);

if (concurrentOps >= 0) DatabaseDescriptor.setConcurrentAccordOps(concurrentOps); else throw new IllegalArgumentException("concurrentOps must be >= 0: " + concurrentOps);

boolean isValidAccordOps(int v) { return v >= 0; }

try { DatabaseDescriptor.setConcurrentAccordOps(ops); } catch (IllegalArgumentException e) { log.error("Invalid accord ops value", e); ops = 0; DatabaseDescriptor.setConcurrentAccordOps(ops); }

When it happens

Trigger: Calling DatabaseDescriptor.setConcurrentAccordOps(n) with n < 0, e.g. setConcurrentAccordOps(-1). Also reachable via JMX/nodetool setters that pass through a user-supplied negative concurrent_operations value.

Common situations: Operators computing the value dynamically (e.g. based on a delta or subtraction) that yields a negative; scripts or automation passing unvalidated integers; copy-paste mistakes in cassandra.yaml manipulation tools.

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

• Invalid accord progress log configuration:
• DC weights must be zero or positive
• %s must be a positive number, got %s
• %s must be greater than zero
• %s must specify at least one DC

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/a1fe0f38a2241e1f. Report an issue: GitHub.