apache/cassandra · error · IllegalArgumentException

Must specify 'op'

Error message

Must specify 'op'

What it means

After parsing an INSERT into accord_command_store_ops, if no 'op' column value was supplied the row cannot dispatch any debug operation, so an IllegalArgumentException("Must specify 'op'") is thrown. Every write to this table must name the CommandStoreOp to run.

Solutions

1. Include the 'op' column with a valid CommandStoreOp enum value (e.g. 'REPLAY', 'SET_PROGRESS_LOG_MODE').
2. List accepted ops via the enum CommandStoreOp in the Cassandra source or DESCRIBE the table.
3. Remove the stray empty INSERT instead of sending an op-less row.

Example fix

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

if (insertValues.get("op") == null || insertValues.get("op").isBlank())
    throw new IllegalArgumentException("accord_command_store_ops inserts must specify 'op'");

try {
    session.execute(insert);
} catch (IllegalArgumentException e) {
    if (e.getMessage().equals("Must specify 'op'")) {
        // add the op column with a valid CommandStoreOp value and retry
    }
}

When it happens

Trigger: INSERTing a row that sets only command_store_id (and optionally 'param') without an 'op' column, or inserting NULL for 'op'.

Common situations: Partially filled INSERT templates; forgetting that virtual-table writes require all meaningful columns; trying to 'clear' a row by omitting op.

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

• COMMAND_STORE_OPS + " is a write-only table"
• metadata + " only supports single partition key queries"
• Must specify 'param' for " + op
• 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/137809c02fd0971b. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/db/virtual/AccordDebugKeyspace.java:2042

            CommandStoreOp op = null;
            String param = null;
            for (int i = 0 ; i < columns.length ; ++i)
            {
                switch (columns[i].name.toString())
                {
                    default: throw new IllegalArgumentException("Unknown column " + columns[i].name.toString());
                    case "op":
                        op = tryParse(values[i], true, CommandStoreOp.class, CommandStoreOp::valueOf);
                        break;
                    case "param":
                        param = (String) values[i];
                        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);

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