Tomcat启动报A child container failed during start问题解决

排查方案，把.xml内无关的所有注释掉，启动程序，如果成功了，就一点点代码还原+重启，直至找到致命的那行代码！（比如web.xml、pom.xml）

报错详情：

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[/MyMaven]]
	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:931)
	at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:850)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1412)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1402)
	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[/MyMaven]]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
	... 6 more
Caused by: java.lang.IllegalArgumentException: The session tracking mode [SSL] requested for context [/MyMaven] is not supported by that context
	at org.apache.catalina.core.ApplicationContext.setSessionTrackingModes(ApplicationContext.java:1069)
	at org.apache.catalina.core.ApplicationContextFacade.setSessionTrackingModes(ApplicationContextFacade.java:626)
	at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1400)
	at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1156)
	at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
	at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
	at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:94)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5063)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	... 6 more

七月 30, 2020 4:43:50 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:931)
	at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:258)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:770)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:688)
	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:353)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:493)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1412)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1402)
	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:942)
	at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:850)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	... 6 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/MyMaven]]
	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:931)
	... 8 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/MyMaven]]
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
	... 6 more
Caused by: java.lang.IllegalArgumentException: The session tracking mode [SSL] requested for context [/MyMaven] is not supported by that context
	at org.apache.catalina.core.ApplicationContext.setSessionTrackingModes(ApplicationContext.java:1069)
	at org.apache.catalina.core.ApplicationContextFacade.setSessionTrackingModes(ApplicationContextFacade.java:626)
	at org.apache.catalina.startup.ContextConfig.configureContext(ContextConfig.java:1400)
	at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1156)
	at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
	at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
	at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:94)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5063)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	... 6 more

没有任何有用的提示，就是启动失败，弹框报错。
问了度娘，记下一些步骤：

1、servlet-api包冲突

• 出现这个问题的原因是导入了servlet-api包，与tomcat7的依赖包servlet-api冲突
• 检查pom.xml是否导入servlet-api
• 加上<scope>provided</scope>之后再次运行，成功启动

2、找到问题了

• 提示很明显了，[SSL] requested表示你的xml有地方配置了SSL请求方式。
• 多看报错提示。
• 排查方案，把.xml内无关的所有注释掉，启动程序，如果成功了，就一点点代码还原+重启，直至找到致命的那行代码！

排查方案，把.xml内无关的所有注释掉，启动程序，如果成功了，就一点点代码还原+重启，直至找到致命的那行代码！（比如web.xml、pom.xml）