apache/cassandra · error · IllegalArgumentException

Must specify 'param' for " + op

Error message

Must specify 'param' for " + op

What it means

For the CommandStoreOps SET_PROGRESS_LOG_MODE and UNSET_PROGRESS_LOG_MODE, the 'param' column is mandatory because it names the ModeFlag to set/unset. When param is null an IllegalArgumentException("Must specify 'param' for <op>") is thrown.

Solutions

1. Supply 'param' with a valid ModeFlag name (e.g. mode enum value used by DefaultProgressLog).
2. If the intent was not a mode change, choose the correct op that takes no param.
3. Verify ModeFlag enum values in the source before writing.

Example fix

// before
INSERT INTO system_views.accord_command_store_ops (command_store_id, op) VALUES (0, 'SET_PROGRESS_LOG_MODE');
// after
INSERT INTO system_views.accord_command_store_ops (command_store_id, op, param) VALUES (0, 'SET_PROGRESS_LOG_MODE', 'NORMAL');

if ((op.equals("SET_PROGRESS_LOG_MODE") || op.equals("UNSET_PROGRESS_LOG_MODE")) && (param == null || param.isBlank()))
    throw new IllegalArgumentException("op " + op + " requires the 'param' column with a ModeFlag value");

try {
    session.execute(insert);
} catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("Must specify 'param' for")) {
        // re-issue the INSERT including param = <ModeFlag>
    }
}

When it happens

Trigger: INSERTing into system_views.accord_command_store_ops with op = 'SET_PROGRESS_LOG_MODE' or 'UNSET_PROGRESS_LOG_MODE' but omitting the 'param' column or leaving it NULL.

Common situations: Assuming mode ops work without an argument like other ops (e.g. REPLAY); templates copied from ops that don't need params.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Must specify 'op'
• COMMAND_STORE_OPS + " is a write-only table"
• metadata + " only supports single partition key queries"
• NODE_OPS + " is a write-only table"
• TXN_OPS + " is a write-only table"

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/54fe75e902d55e16. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/db/virtual/AccordDebugKeyspace.java:2055

                        break;
                }
            }

            if (op == null)
                throw new IllegalArgumentException("Must specify 'op'");

            final AccordService accord = (AccordService) AccordService.unsafeInstance();
            final Node node = accord.node();
            final Function<CommandStore, AsyncResult<?>> function;
            Supplier<AsyncResult<?>> allFunction = null;
            switch (op)
            {
                default: throw new UnhandledEnum(op);
                case SET_PROGRESS_LOG_MODE:
                case UNSET_PROGRESS_LOG_MODE:
                {
                    if (param == null)
                        throw new IllegalArgumentException("Must specify 'param' for " + op);
                    ModeFlag mode = tryParse(param, true, ModeFlag.class, ModeFlag::valueOf);
                    boolean set = op == CommandStoreOp.SET_PROGRESS_LOG_MODE;
                    function = commandStore -> {
                        DefaultProgressLog progressLog = ((DefaultProgressLog)commandStore.unsafeProgressLog());
                        if (set) progressLog.setMode(mode);
                        else progressLog.unsetMode(mode);
                        return AsyncResults.success(null);
                    };
                    break;
                }
                case TRY_EXECUTE_LISTENING:
                {
                    boolean loop;
                    if (param == null) loop = false;
                    else if (param.equalsIgnoreCase("loop")) loop = true;
                    else throw new InvalidRequestException("Unknown param for " + CommandStoreOp.TRY_EXECUTE_LISTENING + ": '" + param + "'; expect only 'loop' or missing");

                    function = commandStore -> commandStore.tryToExecuteListeningTxns(loop);

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