一、问题现象

2023-12-05 17:29:26.373]|[ERROR]|[80978]|[main]|[]|[]|[o.s.boot.SpringApplication              :837]|[Application run failed

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to process import candidates for configuration class [com.upkeep.gateway.GatewayApplication]; nested exception is java.lang.IllegalArgumentException: Could not find class [org.springframework.cloud.client.loadbalancer.reactive.OnNoRibbonDefaultCondition]
	at org.springframework.context.annotation.ConfigurationClassParser.processImports(ConfigurationClassParser.java:610) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser.access$800(ConfigurationClassParser.java:111) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGroupingHandler.lambda$processGroupImports$1(ConfigurationClassParser.java:812) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1540) ~[na:na]
	at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGroupingHandler.processGroupImports(ConfigurationClassParser.java:809) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorHandler.process(ConfigurationClassParser.java:780) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:193) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:319) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:236) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:280) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:96) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:707) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:533) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:62) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:405) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
	at com.upkeep.gateway.GatewayApplication.main(GatewayApplication.java:12) ~[classes/:na]
Caused by: java.lang.IllegalArgumentException: Could not find class [org.springframework.cloud.client.loadbalancer.reactive.OnNoRibbonDefaultCondition]
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:334) ~[spring-core-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConditionEvaluator.getCondition(ConditionEvaluator.java:124) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:96) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:226) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser.processMemberClasses(ConfigurationClassParser.java:372) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:272) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:250) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassParser.processImports(ConfigurationClassParser.java:600) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	... 20 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.cloud.client.loadbalancer.reactive.OnNoRibbonDefaultCondition
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583) ~[na:na]
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) ~[na:na]
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521) ~[na:na]

二、解决办法

1、查看原配置

检查pom文件中的Spring Boot 和 Cloud版本，本次异常对应的版本为：

<parent>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-parent</artifactId>
     <version>2.3.5.RELEASE</version>
     <relativePath/>
</parent>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-commons</artifactId>
    <version>3.1.3</version>
</dependency>

2、修改为新配置

尝试降低版本，发现的可用的Cloud版本为2.2.9.RELEASE，修改如下：

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-commons</artifactId>
    <version>2.2.9.RELEASE</version>
</dependency>

三、原因分析

Spring Boot和Spring Cloud版本有一定的适配关系，详细可以参考官网：https://spring.io/projects/spring-cloud，部分如下：