消费者端代码：

@RestController
@RequestMapping("/demoapi")
public class DemoApi {
    @Reference
    DemoService demoService;

    @RequestMapping("/demo")
    public String demo(String msg){
        return demoService.returnMsg(msg);
    }
}

生产者端代码：

@Service
public class DemoServiceImpl implements DemoService {
    @Override
    public String returnMsg(String msg) {
        return "收到信息："+msg;
    }
}

nacos页面显示已有服务：
服务名 | 分组名称 | 集群数目 | 实例数 | 健康实例数 | 触发保护阈值
providers:cn.haday.cloud.auth.service.DemoService:: | DEFAULT_GROUP | 1 | 1 | 1 | false

我先启动提供者，再启动消费者，然后消费者报错：

Caused by: java.lang.IllegalStateException: Failed to check the status of the service cn.haday.cloud.auth.service.DemoService. No provider available for the service cn.haday.cloud.auth.service.DemoService from the url nacos://localhost:8848/org.apache.dubbo.registry.RegistryService?application=auth-web&dubbo=2.0.2&init=false&interface=cn.haday.cloud.auth.service.DemoService&methods=returnMsg&pid=21252&qos.enable=false&register.ip=192.168.201.134&release=2.7.6&side=consumer&sticky=false&timestamp=1588907594859 to the consumer 192.168.201.134 use dubbo version 2.7.6
	at org.apache.dubbo.config.ReferenceConfig.createProxy(ReferenceConfig.java:349) ~[dubbo-2.7.6.jar:2.7.6]
	at org.apache.dubbo.config.ReferenceConfig.init(ReferenceConfig.java:258) ~[dubbo-2.7.6.jar:2.7.6]
	at org.apache.dubbo.config.ReferenceConfig.get(ReferenceConfig.java:158) ~[dubbo-2.7.6.jar:2.7.6]
	at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.getOrCreateProxy(ReferenceAnnotationBeanPostProcessor.java:274) ~[dubbo-2.7.6.jar:2.7.6]
	at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.doGetInjectedBean(ReferenceAnnotationBeanPostProcessor.java:143) ~[dubbo-2.7.6.jar:2.7.6]
	at com.alibaba.spring.beans.factory.annotation.AbstractAnnotationBeanPostProcessor.getInjectedObject(AbstractAnnotationBeanPostProcessor.java:359) ~[spring-context-support-1.0.6.jar:na]
	at com.alibaba.spring.beans.factory.annotation.AbstractAnnotationBeanPostProcessor$AnnotatedFieldElement.inject(AbstractAnnotationBeanPostProcessor.java:539) ~[spring-context-support-1.0.6.jar:na]
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:130) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
	at com.alibaba.spring.beans.factory.annotation.AbstractAnnotationBeanPostProcessor.postProcessPropertyValues(AbstractAnnotationBeanPostProcessor.java:142) ~[spring-context-support-1.0.6.jar:na]
	... 17 common frames omitted

如果把@reference加上check=false，然后先启动消费者，再启动生产者，就可以调用到。

谁可以帮忙解决下？

我改用zookeeper作为注册中心后，一切正常。