redis/jedis · error · IllegalArgumentException

healthCheckStrategy must not be null

Error message

healthCheckStrategy must not be null

What it means

MultiDbConfig.Builder.healthCheckStrategy(HealthCheckStrategy) wraps the given strategy in a supplier, but rejects null up front with IllegalArgumentException. Building a HealthCheckStrategy with expensive/checked settings (interval, timeout, failuresBeforeFailover) and passing it null is a configuration bug, so the builder fails fast.

Solutions

1. Pass a constructed HealthCheckStrategy instance, e.g. IntervalStrategy or DefaultHealthCheckStrategy.create(hostAndPort, clientConfig).
2. Omit the call entirely to use the built-in default strategy.
3. Null-check your strategy factory output before invoking the builder.

Example fix

// before
HealthCheckStrategy strategy = createStrategy(config); // null when config absent
builder.healthCheckStrategy(strategy); // throws

// after
HealthCheckStrategy strategy = createStrategy(config);
if (strategy == null) {
  strategy = DefaultHealthCheckStrategy.create(host, jedisClientConfig);
}
builder.healthCheckStrategy(strategy);

if (strategy == null) {
  strategy = DefaultHealthCheckStrategy.create(hostAndPort, jedisClientConfig);
}
builder.healthCheckStrategy(strategy);

When it happens

Trigger: Calling MultiDbConfig.Builder.healthCheckStrategy(null), e.g. a strategy built by a helper that returned null or a field not yet initialized.

Common situations: Factories that build strategies conditionally per environment (no strategy defined for local dev), or refactoring where the strategy variable assignment was dropped.

Related errors

• healthCheckStrategySupplier must not be null
• No BDB found matching host
• protocol must not be null
• protocol must not be null
• At least one endpoint must be specified

AI-assisted analysis of redis/jedis@6dac31d4c2 (2026-09-08). Data as JSON: /api/errors/a7191f8901632e54. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/redis/clients/jedis/MultiDbConfig.java:1150

      /**
       * Sets a specific health check strategy instance for this database.
       * <p>
       * This is a convenience method that wraps the provided strategy in a supplier that always
       * returns the same instance. Use this when you have a pre-configured strategy instance.
       * </p>
       * <p>
       * <strong>Note:</strong> The same strategy instance will be reused, so ensure it's
       * thread-safe if multiple databases might use it.
       * </p>
       * @param healthCheckStrategy the health check strategy instance
       * @return this builder instance for method chaining
       * @throws IllegalArgumentException if healthCheckStrategy is null
       * @see #healthCheckStrategySupplier(StrategySupplier)
       */
      public Builder healthCheckStrategy(HealthCheckStrategy healthCheckStrategy) {
        if (healthCheckStrategy == null) {
          throw new IllegalArgumentException("healthCheckStrategy must not be null");
        }
        this.healthCheckStrategySupplier = (hostAndPort, jedisClientConfig) -> healthCheckStrategy;
        return this;
      }

      /**
       * Enables or disables health checks for this database.
       * <p>
       * When health checks are disabled (false), the database will not be proactively monitored for
       * availability. This means:
       * </p>
       * <ul>
       * <li>No background health check threads will be created</li>
       * <li>Failback to this database must be triggered manually</li>
       * <li>The database is assumed to be healthy unless circuit breaker opens</li>
       * </ul>
       * <p>
       * When health checks are enabled (true) and no strategy supplier was previously set, the

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