tomcat startup error:

Error Messages:
Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/ssm]]
Servlet mapping specifies an unknown servlet name [springDispatcherServlet]
error messages:

Severe: Subcontainer start failure
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/ssm]]
	at java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.util.concurrent.FutureTask.get(FutureTask.java:192)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:916)
	at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909)
	at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:343)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:474)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/ssm]]
	at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909)
	... 21 more
Caused by: java.lang.IllegalArgumentException: Servlet mapping specifies an unknown servlet name [springDispatcherServlet]
	at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3179)
	at org.apache.catalina.Context.addServletMappingDecoded(Context.java:881)
	at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1391)
	at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1168)
	at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:774)
	at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:301)
	at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5056)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	... 27 more
	十月 21, 2021 1:52:20 下午 org.apache.catalina.startup.Catalina start
Severe: The required service component failed to start, so Tomcat could not be started
LifecycleException: child container failed to start
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:928)
	at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:343)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:474)
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: child container failed to start
	at java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.util.concurrent.FutureTask.get(FutureTask.java:192)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:916)
	... 13 more
	Caused by: java.lang.IllegalArgumentException: Servlet mapping specifies an unknown servlet name [springDispatcherServlet]
	at org.apache.catalina.core.StandardContext.addServletMappingDecoded(StandardContext.java:3179)
	at org.apache.catalina.Context.addServletMappingDecoded(Context.java:881)
	at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1391)
	at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1168)
	at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:774)
	at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:301)
	at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5056)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	... 27 more

Solution:

In the web.xml configuration, the names of servlet name and servlet mapping are inconsistent, resulting in changing the name in servlet mapping to dispatcher servlet
note:

note: because I have a dispatcher servlet-servlet.xml file, the name should correspond!