Nacos cluster is running with 1.X mode，can‘t accept gRPC request temporarily.

com.alibaba.nacos.api.exception.NacosException: Request nacos server failed: 
	at com.alibaba.nacos.client.naming.remote.gprc.NamingGrpcClientProxy.requestToServer(NamingGrpcClientProxy.java:227) ~[nacos-client-2.0.2.jar!/:na]
	at com.alibaba.nacos.client.naming.remote.gprc.NamingGrpcClientProxy.subscribe(NamingGrpcClientProxy.java:186) ~[nacos-client-2.0.2.jar!/:na]
	at com.alibaba.nacos.client.naming.remote.NamingClientProxyDelegate.subscribe(NamingClientProxyDelegate.java:146) ~[nacos-client-2.0.2.jar!/:na]
	at com.alibaba.nacos.client.naming.NacosNamingService.subscribe(NacosNamingService.java:393) ~[nacos-client-2.0.2.jar!/:na]
	at com.alibaba.cloud.nacos.discovery.NacosWatch.start(NacosWatch.java:123) ~[spring-cloud-starter-alibaba-nacos-discovery-2.2.5.RELEASE.jar!/:2.2.5.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:182) ~[spring-context-5.2.12.RELEASE.jar!/:5.2.12.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor.access0(DefaultLifecycleProcessor.java:53) ~[spring-context-5.2.12.RELEASE.jar!/:5.2.12.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:360) ~[spring-context-5.2.12.RELEASE.jar!/:5.2.12.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:158) ~[spring-context-5.2.12.RELEASE.jar!/:5.2.12.RELEASE]
	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:122) ~[spring-context-5.2.12.RELEASE.jar!/:5.2.12.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:895) ~[spring-context-5.2.12.RELEASE.jar!/:5.2.12.RELEASE]
	at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.finishRefresh(ReactiveWebServerApplicationContext.java:129) ~[spring-boot-2.2.13.RELEASE.jar!/:2.2.13.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:554) ~[spring-context-5.2.12.RELEASE.jar!/:5.2.12.RELEASE]
	at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[spring-boot-2.2.13.RELEASE.jar!/:2.2.13.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.13.RELEASE.jar!/:2.2.13.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:405) ~[spring-boot-2.2.13.RELEASE.jar!/:2.2.13.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.13.RELEASE.jar!/:2.2.13.RELEASE]
	at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:140) ~[spring-boot-2.2.13.RELEASE.jar!/:2.2.13.RELEASE]
	at com.shanyousz.core.launch.ShanyouszApplication.run(ShanyouszApplication.java:35) ~[shanyousz-core-launch-1.0.2-RELEASE.jar!/:na]
	at com.shanyousz.gateway.GateWayApplication.main(GateWayApplication.java:21) ~[classes!/:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
	at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49) ~[shanyousz-gateway.jar:na]
	at org.springframework.boot.loader.Launcher.launch(Launcher.java:108) ~[shanyousz-gateway.jar:na]
	at org.springframework.boot.loader.Launcher.launch(Launcher.java:58) ~[shanyousz-gateway.jar:na]
	at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:88) ~[shanyousz-gateway.jar:na]
Caused by: com.alibaba.nacos.api.exception.NacosException: Nacos cluster is running with 1.X mode, can't accept gRPC request temporarily. Please check the server status or close Double write to force open 2.0 mode. Detail https://nacos.io/en-us/docs/2.0.0-upgrading.html.
	at com.alibaba.nacos.client.naming.remote.gprc.NamingGrpcClientProxy.requestToServer(NamingGrpcClientProxy.java:219) ~[nacos-client-2.0.2.jar!/:na]
	... 27 common frames omitted

异常：Nacos cluster is running with 1.X mode, can't accept gRPC request temporarily. Please check the server status or close Double write to force open 2.0 mode. Detail https://nacos.io/en-us/docs/2.0.0-upgrading.html.

原因：

Nacos2.0版本因为考虑1.x版本的升级用户。所以2.0版本启动时必须先以1.X模式启动。当集群中所有nacos client节点都达到可升级至2.0的状态时，才自动升级成2.0模式。 所以在成功升级2.0模式之前，用grpc注册的服务，在1.X模式下看不到。官方文档截图如下：

解决方案： 

        1、检查所有Nacos client 节点是否都已正常启动

        2、更换 Nacos2.1版本

Nacos 2.1版本默认关闭从1.x版本升级。

参考nacos 2.0.0-bugfix版本，选主失败，此时nacos-client-2.0.0版本服务注册成功，但是控制台不显示 · Issue #5361 · alibaba/nacos · GitHubhttps://github.com/alibaba/nacos/issues/5361