quarkusio/quarkus · error · IllegalStateException

Unable to add command to the current transaction

Error message

Unable to add command to the current transaction

What it means

In transactional Redis commands, each queued command must receive a 'QUEUED' reply. queuedOrDiscard() checks the response; if it is not QUEUED, the whole transaction is discarded and an IllegalStateException is thrown because the command could not be added to the transaction and continuing would leave the MULTI block inconsistent.

Source

Thrown at extensions/redis-client/runtime/src/main/java/io/quarkus/redis/runtime/datasource/AbstractTransactionalCommands.java:20

import io.quarkus.redis.datasource.ReactiveTransactionalRedisCommands;
import io.quarkus.redis.datasource.transactions.ReactiveTransactionalRedisDataSource;
import io.vertx.redis.client.Response;

public class AbstractTransactionalCommands implements ReactiveTransactionalRedisCommands {

    protected final TransactionHolder tx;
    private final ReactiveTransactionalRedisDataSource ds;

    public AbstractTransactionalCommands(ReactiveTransactionalRedisDataSource ds, TransactionHolder tx) {
        this.ds = ds;
        this.tx = tx;
    }

    protected void queuedOrDiscard(Response response) {
        if (!"QUEUED".equals(response.toString())) {
            this.tx.discard();
            throw new IllegalStateException("Unable to add command to the current transaction");
        }
    }

    @Override
    public ReactiveTransactionalRedisDataSource getDataSource() {
        return ds;
    }
}

View on GitHub (pinned to e1c734241f)

Solutions

1. Inspect the discarded transaction's commands for type/key mismatches (WRONGTYPE replies) and fix the offending command.
2. Verify all commands used in the transaction are supported by your Redis server version.
3. Retry the transaction after the failure, since the client discarded it automatically.

Example fix

// before
TxRedisStringCommands<String> strings = tx.string();
strings.set(key, value); // fails if key holds a list -> WRONGTYPE

// after
if (tx.type(key).await().indefinitely().equals("string")) {
    tx.string().set(key, value);
}

// Validate key types before entering the transaction
String type = redis.key().type(key).await().indefinitely();

try (TransactionResult ignored = txResult) {
    tx.string().set(key, value);
} catch (IllegalStateException e) {
    if (e.getMessage().contains("Unable to add command to the current transaction")) {
        // transaction was discarded; inspect command args/types and retry
    }
}

When it happens

Trigger: Inside a Redis transaction (MULTI/EXEC flow via TransactionalRedisDataSource), a command is queued and the server responds with something other than QUEUED — e.g. a WRONGTYPE or syntax error reply during queueing.

Common situations: Calling a command with arguments of the wrong Redis type inside a transaction (e.g. LIST operation on a STRING key); using commands unsupported by the server version; connection issues mid-transaction.

Related errors

• Could not access JTA Transaction to register synchronization
• Error getting the status of the current transaction
• Error getting the current transaction
• Changing timeout via @TransactionConfiguration can only be d
• The Reactive Redis Client must be injected

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/015fd02922d12303. Report an issue: GitHub.