jliuhust opened a new issue, #16178: URL: https://github.com/apache/dubbo/issues/16178
### Pre-check - [x] I am sure that all the content I provide is in English. ### Search before asking - [x] I had searched in the [issues](https://github.com/apache/dubbo/issues?q=is%3Aissue) and found no similar issues. ### Apache Dubbo Component Java SDK (apache/dubbo) ### Dubbo Version Dubbo version: 3.3.6 (issue also exists in 3.2.5+) ### Steps to reproduce this issue We have a Dubbo service that subscribes to multiple ZooKeeper registries. One of them is a weakly dependent ZooKeeper (not critical for our service). We expect the service to start successfully even if this weakly dependent ZooKeeper is down. However, in Dubbo 3.3.6, the service fails to start when the weakly dependent ZooKeeper is unavailable. We tested and found that: Dubbo 3.2.0 ~ 3.2.4: ✅ Starts successfully (as expected) Dubbo 3.2.5 and later: ❌ Startup fails Steps to Reproduce: Configure a Dubbo service with multiple ZooKeeper registries Mark one ZooKeeper as weakly dependent (with check=false) Shut down the weakly dependent ZooKeeper Start the Dubbo service ### What you expected to happen The service should start successfully, ignoring the unavailable weakly dependent ZooKeeper. ### Anything else Configuration Example: <dubbo:registry id="registry_zk" protocol="zookeeper" address="127.0.0.1:2181" check="false" use-as-metadata-center="false" use-as-config-center="false"/> <dubbo:reference registry="registry_zk" id="someId" interface="com.SomeService" version="1.0.0" check="false"/> Error Log: java.lang.NullPointerException: Cannot invoke "org.apache.dubbo.registry.Registry.getUrl()" because "this.registry" is null at org.apache.dubbo.registry.ListenerRegistryWrapper.getUrl(ListenerRegistryWrapper.java:44) at org.apache.dubbo.registry.integration.RegistryDirectory.subscribe(RegistryDirectory.java:147) at org.apache.dubbo.registry.integration.RegistryProtocol.doCreateInvoker(RegistryProtocol.java:667) at org.apache.dubbo.registry.integration.InterfaceCompatibleRegistryProtocol.getInvoker(InterfaceCompatibleRegistryProtocol.java:58) at org.apache.dubbo.registry.client.migration.MigrationInvoker.refreshInterfaceInvoker(MigrationInvoker.java:482) at org.apache.dubbo.registry.client.migration.MigrationInvoker.migrateToApplicationFirstInvoker(MigrationInvoker.java:255) at org.apache.dubbo.registry.client.migration.MigrationRuleHandler.refreshInvoker(MigrationRuleHandler.java:90) at org.apache.dubbo.registry.client.migration.MigrationRuleHandler.doMigrate(MigrationRuleHandler.java:71) at org.apache.dubbo.registry.client.migration.MigrationRuleListener.onRefer(MigrationRuleListener.java:285) at org.apache.dubbo.registry.integration.RegistryProtocol.interceptInvoker(RegistryProtocol.java:630) at org.apache.dubbo.registry.integration.RegistryProtocol.doRefer(RegistryProtocol.java:594) at org.apache.dubbo.registry.integration.RegistryProtocol.refer(RegistryProtocol.java:575) at org.apache.dubbo.rpc.protocol.ProtocolListenerWrapper.refer(ProtocolListenerWrapper.java:83) at org.apache.dubbo.rpc.protocol.ProtocolSecurityWrapper.refer(ProtocolSecurityWrapper.java:112) at org.apache.dubbo.qos.protocol.QosProtocolWrapper.refer(QosProtocolWrapper.java:85) at org.apache.dubbo.rpc.cluster.filter.ProtocolFilterWrapper.refer(ProtocolFilterWrapper.java:69) at org.apache.dubbo.rpc.protocol.ProtocolSerializationWrapper.refer(ProtocolSerializationWrapper.java:55) at org.apache.dubbo.rpc.protocol.InvokerCountWrapper.refer(InvokerCountWrapper.java:48) at org.apache.dubbo.rpc.Protocol$Adaptive.refer(Protocol$Adaptive.java) at org.apache.dubbo.config.ReferenceConfig.createInvoker(ReferenceConfig.java:672) at org.apache.dubbo.config.ReferenceConfig.createProxy(ReferenceConfig.java:502) at org.apache.dubbo.config.ReferenceConfig.init(ReferenceConfig.java:383) at org.apache.dubbo.config.ReferenceConfig.get(ReferenceConfig.java:244) at org.apache.dubbo.config.ReferenceConfigBase.get(ReferenceConfigBase.java:399) at org.apache.dubbo.config.utils.SimpleReferenceCache.destroyReference(SimpleReferenceCache.java:294) at org.apache.dubbo.config.utils.SimpleReferenceCache.destroy(SimpleReferenceCache.java:248) at org.apache.dubbo.config.utils.SimpleReferenceCache.destroy(SimpleReferenceCache.java:271) at org.apache.dubbo.config.deploy.DefaultModuleDeployer.lambda$referServices$6(DefaultModuleDeployer.java:577) at java.base/java.util.concurrent.ConcurrentHashMap$ValuesView.forEach(ConcurrentHashMap.java:4783) at org.apache.dubbo.config.deploy.DefaultModuleDeployer.referServices(DefaultModuleDeployer.java:539) at org.apache.dubbo.config.deploy.DefaultModuleDeployer.startSync(DefaultModuleDeployer.java:186) at org.apache.dubbo.config.deploy.DefaultModuleDeployer.start(DefaultModuleDeployer.java:159) at org.apache.dubbo.config.spring.context.DubboDeployApplicationListener.onContextRefreshedEvent(DubboDeployApplicationListener.java:167) at org.apache.dubbo.config.spring.context.DubboDeployApplicationListener.onApplicationEvent(DubboDeployApplicationListener.java:153) at org.apache.dubbo.config.spring.context.DubboDeployApplicationListener.onApplicationEvent(DubboDeployApplicationListener.java:52) at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:178) at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:171) at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:145) at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:430) at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:387) at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:952) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:594) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:732) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:409) at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) ### Do you have a (mini) reproduction demo? - [ ] Yes, I have a minimal reproduction demo to help resolve this issue more effectively! ### Are you willing to submit a pull request to fix on your own? - [ ] Yes I am willing to submit a pull request on my own! ### Code of Conduct - [x] I agree 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