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Unable to establish a connection to Redis Cluster
Bug Report
I am facing connection issues after upgrading our AWS ElastiCache Redis cluster engine version from 6.2.2 to 7.1. No application-side code changes were made — the only change was the Redis engine version. We are still using the same Redis client version: lettuce-core:5.1.4.RELEASE.
Error logs:
2025-12-08T07:46:02.023Z level=INFO hostIP= correlationId= thread=RMI TCP Connection(5)-192.168.1.44 component=org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/] message="Initializing Spring DispatcherServlet 'dispatcherServlet'"
2025-12-08T07:46:03.145Z level=INFO hostIP= correlationId= thread=RMI TCP Connection(4)-192.168.1.44 component=io.lettuce.core.EpollProvider message="Starting without optional epoll library"
2025-12-08T07:46:03.153Z level=INFO hostIP= correlationId= thread=RMI TCP Connection(4)-192.168.1.44 component=io.lettuce.core.KqueueProvider message="Starting without optional kqueue library"
2025-12-08T07:46:03.442Z level=WARN hostIP= correlationId= thread=lettuce-nioEventLoop-6-1 component=io.lettuce.core.cluster.topology.ClusterTopologyRefresh message="Unable to connect to {my_ec_redis_endpoint}:6379"
java.util.concurrent.CompletionException: io.netty.channel.ConnectTimeoutException: connection timed out: {my_ec_redis_endpoint}/{IP}:6379
at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:292)
at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:308)
at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:607)
at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:591)
at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:488)
at java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:1990)
at io.lettuce.core.AbstractRedisClient.lambda$initializeChannelAsync0$4(AbstractRedisClient.java:329)
at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:577)
at io.netty.util.concurrent.DefaultPromise.notifyListeners0(DefaultPromise.java:570)
at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:549)
at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:490)
at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:615)
at io.netty.util.concurrent.DefaultPromise.setFailure0(DefaultPromise.java:608)
at io.netty.util.concurrent.DefaultPromise.tryFailure(DefaultPromise.java:117)
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe$1.run(AbstractNioChannel.java:263)
at io.netty.util.concurrent.PromiseTask.runTask(PromiseTask.java:98)
at io.netty.util.concurrent.ScheduledFutureTask.run(ScheduledFutureTask.java:170)
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:164)
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java)
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.lang.Thread.run(Thread.java:750)
Caused by: io.netty.channel.ConnectTimeoutException: connection timed out: {my_ec_redis_endpoint}/{IP}:6379
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe$1.run(AbstractNioChannel.java:261)
... 10 common frames omitted
2025-12-08T07:46:03.450Z level=WARN hostIP= correlationId= thread=RMI TCP Connection(4)-192.168.1.44 component=org.springframework.boot.actuate.redis.RedisHealthIndicator message="Redis health check failed"
org.springframework.data.redis.connection.PoolException: Could not get a resource from the pool; nested exception is io.lettuce.core.RedisException: Cannot retrieve initial cluster partitions from initial URIs [RedisURI [host='masterdata-ec-cluster-test-v7.u1fzgq.clustercfg.usw2.cache.amazonaws.com', port=6379]]
at org.springframework.data.redis.connection.lettuce.LettucePoolingConnectionProvider.getConnection(LettucePoolingConnectionProvider.java:86)
at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory$SharedConnection.getNativeConnection(LettuceConnectionFactory.java:1085)
at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory$SharedConnection.getConnection(LettuceConnectionFactory.java:1065)
at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory.getClusterConnection(LettuceConnectionFactory.java:362)
at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory.getConnection(LettuceConnectionFactory.java:332)
at org.springframework.data.redis.core.RedisConnectionUtils.doGetConnection(RedisConnectionUtils.java:132)
at org.springframework.data.redis.core.RedisConnectionUtils.getConnection(RedisConnectionUtils.java:95)
at org.springframework.data.redis.core.RedisConnectionUtils.getConnection(RedisConnectionUtils.java:82)
at org.springframework.boot.actuate.redis.RedisHealthIndicator.doHealthCheck(RedisHealthIndicator.java:56)
at org.springframework.boot.actuate.health.AbstractHealthIndicator.health(AbstractHealthIndicator.java:84)
at org.springframework.boot.actuate.health.CompositeHealthIndicator.health(CompositeHealthIndicator.java:98)
at org.springframework.boot.actuate.health.HealthEndpoint.health(HealthEndpoint.java:50)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:246)
at org.springframework.boot.actuate.endpoint.invoke.reflect.ReflectiveOperationInvoker.invoke(ReflectiveOperationInvoker.java:76)
at org.springframework.boot.actuate.endpoint.annotation.AbstractDiscoveredOperation.invoke(AbstractDiscoveredOperation.java:61)
at org.springframework.boot.actuate.endpoint.jmx.EndpointMBean.invoke(EndpointMBean.java:126)
at org.springframework.boot.actuate.endpoint.jmx.EndpointMBean.invoke(EndpointMBean.java:99)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1468)
at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1309)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1401)
at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829)
at sun.reflect.GeneratedMethodAccessor280.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:357)
at sun.rmi.transport.Transport$1.run(Transport.java:200)
at sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:834)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:750)
Caused by: io.lettuce.core.RedisException: Cannot retrieve initial cluster partitions from initial URIs [RedisURI [host='{my_ec_redis_endpoint}', port=6379]]
at io.lettuce.core.cluster.RedisClusterClient.loadPartitions(RedisClusterClient.java:865)
at io.lettuce.core.cluster.RedisClusterClient.initializePartitions(RedisClusterClient.java:819)
at io.lettuce.core.cluster.RedisClusterClient.connect(RedisClusterClient.java:345)
at org.springframework.data.redis.connection.lettuce.ClusterConnectionProvider.getConnection(ClusterConnectionProvider.java:85)
at org.springframework.data.redis.connection.lettuce.LettucePoolingConnectionProvider.lambda$null$0(LettucePoolingConnectionProvider.java:74)
at io.lettuce.core.support.ConnectionPoolSupport$RedisPooledObjectFactory.create(ConnectionPoolSupport.java:209)
at io.lettuce.core.support.ConnectionPoolSupport$RedisPooledObjectFactory.create(ConnectionPoolSupport.java:199)
at org.apache.commons.pool2.BasePooledObjectFactory.makeObject(BasePooledObjectFactory.java:58)
at org.apache.commons.pool2.impl.GenericObjectPool.create(GenericObjectPool.java:874)
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:417)
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:346)
at io.lettuce.core.support.ConnectionPoolSupport$1.borrowObject(ConnectionPoolSupport.java:122)
at io.lettuce.core.support.ConnectionPoolSupport$1.borrowObject(ConnectionPoolSupport.java:117)
at org.springframework.data.redis.connection.lettuce.LettucePoolingConnectionProvider.getConnection(LettucePoolingConnectionProvider.java:80)
... 43 common frames omitted
Caused by: io.lettuce.core.RedisConnectionException: Unable to establish a connection to Redis Cluster
at io.lettuce.core.cluster.topology.AsyncConnections.get(AsyncConnections.java:84)
at io.lettuce.core.cluster.topology.ClusterTopologyRefresh.loadViews(ClusterTopologyRefresh.java:68)
at io.lettuce.core.cluster.RedisClusterClient.doLoadPartitions(RedisClusterClient.java:871)
at io.lettuce.core.cluster.RedisClusterClient.loadPartitions(RedisClusterClient.java:844)
... 56 common frames omitted
Suppressed: io.lettuce.core.RedisConnectionException: Unable to connect to {my_ec_redis_endpoint}:6379
at io.lettuce.core.cluster.topology.ClusterTopologyRefresh.lambda$getConnections$2(ClusterTopologyRefresh.java:231)
at java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:774)
at java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:750)
at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:488)
at java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:1990)
at io.lettuce.core.AbstractRedisClient.lambda$initializeChannelAsync0$4(AbstractRedisClient.java:329)
at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:577)
at io.netty.util.concurrent.DefaultPromise.notifyListeners0(DefaultPromise.java:570)
at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:549)
at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:490)
at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:615)
at io.netty.util.concurrent.DefaultPromise.setFailure0(DefaultPromise.java:608)
at io.netty.util.concurrent.DefaultPromise.tryFailure(DefaultPromise.java:117)
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe$1.run(AbstractNioChannel.java:263)
at io.netty.util.concurrent.PromiseTask.runTask(PromiseTask.java:98)
at io.netty.util.concurrent.ScheduledFutureTask.run(ScheduledFutureTask.java:170)
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:164)
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java)
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
... 1 common frames omitted
Caused by: java.util.concurrent.CompletionException: io.netty.channel.ConnectTimeoutException: connection timed out: {my_ec_redis_endpoint}/{IP}:6379
at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:292)
at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:308)
at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:607)
at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:591)
... 21 common frames omitted
Caused by: io.netty.channel.ConnectTimeoutException: connection timed out: {my_ec_redis_endpoint}/{IP}:6379
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe$1.run(AbstractNioChannel.java:261)
... 10 common frames omitted
Service version details: Java 8 Spring boot 2.1.5.RELEASE Current lettuce lib: lettuce-core-5.1.4.RELEASE
Client creation code:
@Bean("redisConf")
public RedisClusterConfiguration redisConfiguration() {
if (properties.getRedisPort() != null) {
return new RedisClusterConfiguration()
.clusterNode(properties.getRedisEndpoint(), Integer.valueOf(properties.getRedisPort()));
}
return new RedisClusterConfiguration()
.clusterNode(properties.getRedisEndpoint(), 6379);
}
@Bean("redisConfFactory")
public RedisConnectionFactory redisConnectionFactory(
@Qualifier("redisConf") RedisClusterConfiguration redisConfiguration) {
return new LettuceConnectionFactory(redisConfiguration, createLettuceClientConfig());
}
@Bean("redisTemplate")
public StringRedisTemplate redisTemplate(
@Qualifier("redisConfFactory") RedisConnectionFactory factory) {
return new StringRedisTemplate(factory);
}
@Bean
public RedisHashMapper redisHashMapper(ObjectMapper mapper) {
return new RedisHashMapper(mapper);
}
private LettuceClientConfiguration createLettuceClientConfig() {
GenericObjectPoolConfig genericObjectPoolConfig = createGenericObjectPoolConfig();
final SocketOptions socketOptions = SocketOptions.builder()
.connectTimeout(Duration.ofMillis(MAX_TIMEOUT))
.build();
ClusterTopologyRefreshOptions topologyRefreshOptions = ClusterTopologyRefreshOptions.builder()
.enableAllAdaptiveRefreshTriggers()
.enablePeriodicRefresh(Duration.ofSeconds(TOPOLOGY_REFRESH_INTERVAL))
.build();
final ClientOptions clusterClientOptions = ClusterClientOptions.builder()
.socketOptions(socketOptions)
.topologyRefreshOptions(topologyRefreshOptions)
.build();
return LettucePoolingClientConfiguration.builder()
.clientOptions(clusterClientOptions)
.poolConfig(genericObjectPoolConfig)
.build();
}
private GenericObjectPoolConfig createGenericObjectPoolConfig() {
GenericObjectPoolConfig genericObjectPoolConfig = new GenericObjectPoolConfig();
genericObjectPoolConfig.setMaxIdle(MAX_IDLE);
genericObjectPoolConfig.setMaxWaitMillis(MAX_WAIT);
genericObjectPoolConfig.setMaxTotal(MAX_ACTIVE);
genericObjectPoolConfig.setMinIdle(MIN_IDLE);
return genericObjectPoolConfig;
}
Also, I would like to see proper guidance to resolve the issue.Thanks
Hey @mjjainmeet
io.lettuce.core.RedisConnectionException: Unable to connect to {my_ec_redis_endpoint}:6379
Seems to me like a connectivity issue - are you able to connect to the given address and port from the machine where lettuce is being deployed?
Could you let us know what are the values of the timeout settings you are setting? Could they be too aggressive?
Overall it would be close to impossible for the team to help with connectivity issues, you need to trace the problem on your end, as this is specific to your environment.