redis/jedis · error · JedisConnectionException

JedisConnectionException

Error message

JedisConnectionException

What it means

TrackingConnectionPool.makeObject wraps any non-JedisConnectionException thrown while creating a pooled connection into a new JedisConnectionException whose cause is the original exception. Genuine connection failures (JedisConnectionException) are rethrown unchanged; everything else — DNS resolution errors, factory configuration problems, IO classes, runtime errors — surfaces as this wrapping exception.

Solutions

1. Inspect the exception's cause chain (getCause()) to find the root error — the wrapper itself carries no detail.
2. Fix the underlying cause: correct DNS/host, TLS settings, or ConnectionFactory configuration.
3. If a custom factory is in use, ensure it either returns a connection or throws JedisConnectionException directly.
4. Test endpoint reachability (redis-cli PING / nslookup) to separate DNS/network issues from client bugs.

Example fix

// before
} catch (Exception e) {
  throw new JedisConnectionException(e); // opaque without cause handling
}
// after
try {
  Connection c = pool.getResource();
} catch (JedisConnectionException e) {
  Throwable root = e;
  while (root.getCause() != null) root = root.getCause();
  log.error("connection setup failed: {}", root.getMessage(), root); // diagnose real cause
}

try { InetAddress.getByName(host); } catch (UnknownHostException e) { /* fix hostname before init */ }

try {
  conn = pool.getResource();
} catch (JedisConnectionException e) {
  Throwable root = e;
  while (root.getCause() != null) root = root.getCause();
  log.error("connection setup failed: {}", root.getMessage(), root);
}

When it happens

Trigger: Connection factory throws a non-JedisConnectionException during super.makeObject(): unknown host (UnknownHostException wrapped), socket/SSL initialization errors that are not JedisConnectionException, misconfigured ConnectionFactory, or any RuntimeException from the underlying connection setup.

Common situations: Wrong hostname/DNS entries for a database endpoint; SSL/TLS misconfiguration on the socket factory; classpath or JDK-level errors inside the connection factory; programming errors in custom ConnectionFactory implementations.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

• Failed to create connection!
• Pool is closed!
• Failed to evict connections from pool
• Endpoint does not exist.
• It is not allowed to create Transaction from this

AI-assisted analysis of redis/jedis@6dac31d4c2 (2026-09-08). Data as JSON: /api/errors/fbedcd79629c2b1a. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/redis/clients/jedis/mcf/TrackingConnectionPool.java:56

    }

    @Override
    public PooledObject<Connection> makeObject() throws Exception {
      if (failFast) {
        throw new JedisConnectionException("Failed to create connection!");
      }
      try {
        PooledObject<Connection> object = super.makeObject();
        // this can make a marginal improvement on fast failover duration!
        if (failFast) {
          object.getObject().close();
          throw new JedisConnectionException("Failed to create connection!");
        }
        return object;
      } catch (JedisConnectionException e) {
        throw e;
      } catch (Exception e) {
        throw new JedisConnectionException(e);
      }
    }

    @Override
    protected void initialize(Connection conn) {
      // Track the connection while it is being initialized so forceDisconnect() can interrupt
      // a thread that is blocked inside HELLO/AUTH/CLIENT round-trips.
      factoryTrackedObjects.add(conn);
      try {
        super.initialize(conn);
      } finally {
        factoryTrackedObjects.remove(conn);
      }
    }

    public void forceDisconnect() {
      for (Connection connection : factoryTrackedObjects) {
        try {

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