异常如下
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘gatewayConfigurationService’ defined in class path resource [org/springframework/cloud/gateway/config/GatewayAutoConfiguration.class]: Unsatisfied dependency expressed through method ‘gatewayConfigurationService’ parameter 1; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type ‘org.springframework.core.convert.ConversionService’ available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Qualifier(value=webFluxConversionService)}
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:799) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:540) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1341) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1181) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:556) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:897) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:879) ~[spring-context-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) ~[spring-context-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.9.RELEASE.jar:2.3.9.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) [spring-boot-2.3.9.RELEASE.jar:2.3.9.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.3.9.RELEASE.jar:2.3.9.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:405) [spring-boot-2.3.9.RELEASE.jar:2.3.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.3.9.RELEASE.jar:2.3.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) [spring-boot-2.3.9.RELEASE.jar:2.3.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.3.9.RELEASE.jar:2.3.9.RELEASE]
at com.offcn.gateway.GateWayStart.main(GateWayStart.java:11) [classes/:na]
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type ‘org.springframework.core.convert.ConversionService’ available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Qualifier(value=webFluxConversionService)}
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1717) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1273) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1227) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:886) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:790) ~[spring-beans-5.2.13.RELEASE.jar:5.2.13.RELEASE]
… 20 common frames omitted
原因：

org.springframework.cloud
spring-cloud-starter-gateway

里面已经有web的包，项目里不能再有web的依赖
解决办法：
删除web的依赖