The above pile of tomcat startup prompt information is omitted, the following is the specific information of the error:
org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 15
at org.apache.tomcat.util.bcel .classfile.Constant.readConstant(Constant.java:131)
at org.apache.tomcat.util.bcel.classfile.ConstantPool.<init>(ConstantPool.java:60)
at org.apache.tomcat.util.bcel.classfile .ClassParser.readConstantPool(ClassParser.java:209)
at org.apache.tomcat.util.bcel.classfile.ClassParser.parse(ClassParser.java:119)
at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java :1911)
at org.apache.catalina.startup.ContextConfig.processAnnotationsJar(ContextConfig.java:1800)
at org.apache.catalina.startup.ContextConfig.processAnnotationsUrl(ContextConfig.java:1759)
at org.apache.catalina.startup.ContextConfig.processAnnotations(ContextConfig.java:1745)
at org.apache.catalina.startup.ContextConfig.webConfig (ContextConfig.java:1249)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:876)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:317)
at org.apache. catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:89)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java: 5061)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:812)
at org.apache.catalina.core.ContainerBase.addChild (ContainerBase.java:787)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:607)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1044)
at org.apache. catalina.startup.HostConfig.deployDirectories(HostConfig.java:967)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:472)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java: 1346)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:294)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:89)
at org.apache.catalina.core.ContainerBase.backgroundProcess (ContainerBase.java:1233)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1391)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1401)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1380)
at java.lang.Thread.run(Thread.java:745)

 First paste the error message in the control column, the following is the solution:

First of all, I deleted all the deployed projects, and then restarted tomcat, it can start successfully, and can see the welcome page, and then deploy a few small servlet test pages written by myself in turn, it is fine, and it runs normally.

However, this error was reported when some projects were deployed. The error message on the Internet seems to be very small. After all the hardships, I finally found a usable solution. The specifics are posted as follows to warn myself and benefit future generations:

{tomcat path}/conf/web.xml modification method:

<web-app version=”3.0″ xmlns=”http://java.sun.com/xml/ns/javaee” xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance” xsi :schemaLocation=”http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd” metadata-complete=”true”>

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