Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2021-11-30 14:40:01.336 ERROR 14864 --- [ main] o.s.boot.SpringApplication : Application run failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'memberController': Unsatisfied dependency expressed through field 'couponFeignService'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.wang.hgmall.member.feign.CouponFeignService': Unexpected exception during bean creation; nested exception is java.lang.IllegalStateException: No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-loadbalancer?
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:659) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:639) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1431) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:619) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:944) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.13.jar:5.3.13]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.13.jar:5.3.13]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730) [spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412) [spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:302) [spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301) [spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1290) [spring-boot-2.6.0.jar:2.6.0]
at com.wang.hgmall.member.MemberApplication.main(MemberApplication.java:20) [classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.wang.hgmall.member.feign.CouponFeignService': Unexpected exception during bean creation; nested exception is java.lang.IllegalStateException: No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-loadbalancer?
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1380) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:656) ~[spring-beans-5.3.13.jar:5.3.13]
... 20 common frames omitted
Caused by: java.lang.IllegalStateException: No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-loadbalancer?
at org.springframework.cloud.openfeign.FeignClientFactoryBean.loadBalance(FeignClientFactoryBean.java:376) ~[spring-cloud-openfeign-core-3.1.0-RC1.jar:3.1.0-RC1]
at org.springframework.cloud.openfeign.FeignClientFactoryBean.getTarget(FeignClientFactoryBean.java:421) ~[spring-cloud-openfeign-core-3.1.0-RC1.jar:3.1.0-RC1]
at org.springframework.cloud.openfeign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:396) ~[spring-cloud-openfeign-core-3.1.0-RC1.jar:3.1.0-RC1]
at org.springframework.cloud.openfeign.FeignClientsRegistrar.lambda$registerFeignClient$0(FeignClientsRegistrar.java:235) ~[spring-cloud-openfeign-core-3.1.0-RC1.jar:3.1.0-RC1]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.obtainFromSupplier(AbstractAutowireCapableBeanFactory.java:1249) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1191) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.13.jar:5.3.13]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.13.jar:5.3.13]
... 28 common frames omitted

Disconnected from the target VM, address: '127.0.0.1:51270', transport: 'socket'

Process finished with exit code 1

 错误：

Caused by: java.lang.IllegalStateException: No Feign Client for loadBalancing defined. 

错误的原因是：

SpringCloud Feign在Hoxton.M2 RELEASED版本之后不再使用Ribbon而是使用spring-cloud-loadbalancer，所以不引入spring-cloud-loadbalancer就会出现以上错误

 

解决方法：

       引入spring-cloud-loadbalancer就可以解决

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-loadbalancer</artifactId>
</dependency>
 <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
                </exclusion>
            </exclusions>
   </dependency>

最后就可以成功启动了！

2021-11-30 14:47:48.614  INFO 6800 --- [           main] o.s.c.openfeign.FeignClientFactoryBean   : For 'hgmall-coupon' URL not provided. Will try picking an instance via load-balancing.
2021-11-30 14:47:51.179  INFO 6800 --- [           main] o.s.cloud.commons.util.InetUtils         : Cannot determine local hostname
2021-11-30 14:47:53.513  INFO 6800 --- [           main] o.s.cloud.commons.util.InetUtils         : Cannot determine local hostname
2021-11-30 14:47:53.537  WARN 6800 --- [           main] iguration$LoadBalancerCaffeineWarnLogger : Spring Cloud LoadBalancer is currently working with the default cache. You can switch to using Caffeine cache, by adding it and org.springframework.cache.caffeine.CaffeineCacheManager to the classpath.
2021-11-30 14:47:53.777  INFO 6800 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8002 (http) with context path ''
2021-11-30 14:47:53.790  INFO 6800 --- [           main] c.a.c.n.registry.NacosServiceRegistry    : nacos registry, DEFAULT_GROUP hg 192.168.110.70:8002 register finished
2021-11-30 14:47:56.054  INFO 6800 --- [           main] o.s.cloud.commons.util.InetUtils         : Cannot determine local hostname
2021-11-30 14:47:56.060  INFO 6800 --- [           main] c.wang.hgmall.member.MemberApplication   : Started MemberApplication in 13.656 seconds (JVM running for 15.312)