org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat

异常分析

org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:162) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:582) ~[spring-context-5.3.3.jar:5.3.3]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:144) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:767) [spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:426) [spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:326) [spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1311) [spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1300) [spring-boot-2.4.2.jar:2.4.2]
	at com.myself.study.SpringDemoApplication.main(SpringDemoApplication.java:13) [classes/:na]
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:142) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.(TomcatWebServer.java:104) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:451) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:200) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:181) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:159) ~[spring-boot-2.4.2.jar:2.4.2]
	... 9 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'formContentFilter' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.web.servlet.filter.OrderedFormContentFilter]: Factory method 'formContentFilter' threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/AnnotationIntrospector$XmlExtensions
	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:658) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:486) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1336) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1179) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:571) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:531) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:213) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:212) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:175) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:170) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAdaptableBeans(ServletContextInitializerBeans.java:155) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.servlet.ServletContextInitializerBeans.(ServletContextInitializerBeans.java:87) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.getServletContextInitializerBeans(ServletWebServerApplicationContext.java:259) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.selfInitialize(ServletWebServerApplicationContext.java:233) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.springframework.boot.web.embedded.tomcat.TomcatStarter.onStartup(TomcatStarter.java:53) ~[spring-boot-2.4.2.jar:2.4.2]
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_351]
	at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134) ~[na:1.8.0_351]
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:843) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_351]
	at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134) ~[na:1.8.0_351]
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.StandardService.startInternal(StandardService.java:434) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.apache.catalina.startup.Tomcat.start(Tomcat.java:486) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:123) ~[spring-boot-2.4.2.jar:2.4.2]
	... 14 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.web.servlet.filter.OrderedFormContentFilter]: Factory method 'formContentFilter' threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/AnnotationIntrospector$XmlExtensions
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.3.3.jar:5.3.3]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ~[spring-beans-5.3.3.jar:5.3.3]
	... 55 common frames omitted
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/AnnotationIntrospector$XmlExtensions
	at com.fasterxml.jackson.dataformat.xml.JacksonXmlModule._constructIntrospector(JacksonXmlModule.java:130) ~[jackson-dataformat-xml-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.dataformat.xml.JacksonXmlModule.setupModule(JacksonXmlModule.java:69) ~[jackson-dataformat-xml-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ObjectMapper.registerModule(ObjectMapper.java:819) ~[jackson-databind-2.11.4.jar:2.11.4]
	at com.fasterxml.jackson.dataformat.xml.XmlMapper.(XmlMapper.java:169) ~[jackson-dataformat-xml-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.dataformat.xml.XmlMapper.(XmlMapper.java:153) ~[jackson-dataformat-xml-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.dataformat.xml.XmlMapper.(XmlMapper.java:149) ~[jackson-dataformat-xml-2.14.2.jar:2.14.2]
	at org.springframework.http.converter.json.Jackson2ObjectMapperBuilder$XmlObjectMapperInitializer.create(Jackson2ObjectMapperBuilder.java:920) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.http.converter.json.Jackson2ObjectMapperBuilder.build(Jackson2ObjectMapperBuilder.java:675) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter.(MappingJackson2XmlHttpMessageConverter.java:52) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter.(AllEncompassingFormHttpMessageConverter.java:104) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.web.filter.FormContentFilter.(FormContentFilter.java:61) ~[spring-web-5.3.3.jar:5.3.3]
	at org.springframework.boot.web.servlet.filter.OrderedFormContentFilter.(OrderedFormContentFilter.java:29) ~[spring-boot-2.4.2.jar:2.4.2]
	at 

异常原因：
Maven依赖的SpringBoot版本和Jackson版本冲突,，我的SpringBoot版本是2.3.0.RELEASE，Jackson版本是2.14.2。

Maven依赖如下：

<parent>
	<groupId>org.springframework.bootgroupId>
	<artifactId>spring-boot-starter-parentartifactId>
	<version>2.3.0.RELEASEversion>
parent>
<dependencies>
	<dependency>
	    <groupId>org.springframework.bootgroupId>
	    <artifactId>spring-boot-starter-webartifactId>
	dependency>
	<dependency>
	    <groupId>com.fasterxml.jackson.dataformatgroupId>
	    <artifactId>jackson-dataformat-xmlartifactId>
	    <version>2.14.2version>
	dependency>
	<dependency>
	    <groupId>com.fasterxml.jackson.coregroupId>
	    <artifactId>jackson-annotationsartifactId>
	    <version>2.14.2version>
	dependency>
 dependencies>

异常解决

修改Jackson依赖版本为2.11.4，重新加载Maven。

<dependencies>
	<dependency>
	    <groupId>org.springframework.bootgroupId>
	    <artifactId>spring-boot-starter-webartifactId>
	dependency>
	<dependency>
	    <groupId>com.fasterxml.jackson.dataformatgroupId>
	    <artifactId>jackson-dataformat-xmlartifactId>
	    <version>2.11.4version>
	dependency>
	<dependency>
	    <groupId>com.fasterxml.jackson.coregroupId>
	    <artifactId>jackson-annotationsartifactId>
	    <version>2.11.4version>
	dependency>
dependencies>

项目启动成功。