A child container failed during start Tomcat error prompt

Java Web project startup error: A child Container failed during start
complete error message is as follows: 

严重: A child container failed during start  
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/testcs_dn-admin-web]]  
    at java.util.concurrent.FutureTask.report(Unknown Source)  
    at java.util.concurrent.FutureTask.get(Unknown Source)  
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)  
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:799)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)  
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)  
    at java.util.concurrent.FutureTask.run(Unknown Source)  
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)  
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)  
    at java.lang.Thread.run(Unknown Source)  
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/testcs_dn-admin-web]]  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)  
    ... 6 more  
Caused by: java.lang.IllegalArgumentException: Servlet mapping specifies an unknown servlet name Action  
    at org.apache.catalina.core.StandardContext.addServletMapping(StandardContext.java:3275)  
    at org.apache.catalina.core.StandardContext.addServletMapping(StandardContext.java:3254)  
    at org.apache.catalina.deploy.WebXml.configureContext(WebXml.java:1430)  
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1344)  
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:876)  
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:374)  
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)  
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)  
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5355)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    ... 6 more  

十二月 09, 2014 2:21:25 下午 org.apache.catalina.core.ContainerBase startInternal  
严重: A child container failed during start  
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]  
    at java.util.concurrent.FutureTask.report(Unknown Source)  
    at java.util.concurrent.FutureTask.get(Unknown Source)  
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)  
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:300)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:731)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    at org.apache.catalina.startup.Catalina.start(Catalina.java:689)  
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)  
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)  
    at java.lang.reflect.Method.invoke(Unknown Source)  
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:321)  
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:455)  
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)  
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)  
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)  
    at java.util.concurrent.FutureTask.run(Unknown Source)  
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)  
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)  
    at java.lang.Thread.run(Unknown Source)  
Caused by: org.apache.catalina.LifecycleException: A child container failed during start  
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131)  
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:799)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    ... 6 more  

十二月 09, 2014 2:21:25 下午 org.apache.catalina.startup.Catalina start  
严重: The required Server component failed to start so Tomcat is unable to start.  
org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8006]]  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)  
    at org.apache.catalina.startup.Catalina.start(Catalina.java:689)  
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)  
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)  
    at java.lang.reflect.Method.invoke(Unknown Source)  
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:321)  
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:455)  
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]]  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)  
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:731)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    ... 7 more  
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]]  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)  
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    ... 9 more  
Caused by: org.apache.catalina.LifecycleException: A child container failed during start  
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131)  
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:300)  
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)  
    ... 11 more  

十二月 09, 2014 2:21:25 下午 org.apache.coyote.AbstractProtocol pause  
信息: Pausing ProtocolHandler ["http-bio-8081"]  
十二月 09, 2014 2:21:25 下午 org.apache.coyote.AbstractProtocol pause  
信息: Pausing ProtocolHandler ["ajp-bio-8010"]  
十二月 09, 2014 2:21:25 下午 org.apache.catalina.core.StandardService stopInternal  
信息: Stopping service Catalina  
十二月 09, 2014 2:21:25 下午 org.apache.coyote.AbstractProtocol destroy  
信息: Destroying ProtocolHandler ["http-bio-8081"]  
十二月 09, 2014 2:21:25 下午 org.apache.coyote.AbstractProtocol destroy  
信息: Destroying ProtocolHandler ["ajp-bio-8010"]

solution:
the key to solving this problem is in the error message:

Servlet mapping specifies an unknown servlet name Action

open the “SRC \main\webapp\ web-inf \web.xml” file under the project and look for nodes similar to the following: 

<servlet-mapping>
    <servlet-name>kaptcha</servlet-name>
    <url-pattern>/valicode.jpg</url-pattern>
</servlet-mapping>

Check

& lt; url-pattern> The path of the child node is correct. If correct, it depends on whether the relative path is used elsewhere and the absolute path is used here. In other words, for/valicod.jpg, remove the “/”

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