Solution for Caused by: java.lang.NoClassDefFoundError: oracle/i18n/util/LocaleMapper

This error can happen if you have
xmlparserv2.jar
or
xmlparserv2_sans_jaxp_services.jar
in your libext folder. Please remove it if it is there and restart FlexDeploy.
The full stack trace looks like this:
Fri Apr 05 13:19:46 CDT 2024 - 1 - SEVERE - null - null - null - org.apache.catalina.startup.HostConfig.deployDirectory - Error deploying web application directory [/u01/flexdeploy/apache-tomcat-flexdeploy/webapps/flexdeploy]
java.lang.IllegalStateException: Error starting child
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:686)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:658)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:661)
        at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1175)
        at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1888)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        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:112)
        at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1086)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:470)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1584)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:312)
        at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:114)
        at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:402)
        at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:345)
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:893)
        at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:794)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1332)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1322)
        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:866)
        at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:248)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
        at org.apache.catalina.core.StandardService.startInternal(StandardService.java:433)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
        at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:925)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:735)
        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:345)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:473)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/flexdeploy]]
        at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:419)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:186)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:683)
        ... 37 more
Caused by: java.lang.NoClassDefFoundError: oracle/i18n/util/LocaleMapper
        at oracle.xml.parser.v2.XMLReader.setEncoding(XMLReader.java:996)
        at oracle.xml.parser.v2.XMLReader.checkXMLDecl(XMLReader.java:3576)
        at oracle.xml.parser.v2.XMLReader.pushXMLReader(XMLReader.java:586)
        at oracle.xml.parser.v2.XMLReader.pushXMLReader(XMLReader.java:290)
        at oracle.xml.parser.v2.XMLParser.parse(XMLParser.java:245)
        at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1535)
        at org.apache.tomcat.util.descriptor.tld.TldParser.parse(TldParser.java:77)
        at org.apache.jasper.servlet.TldScanner.parseTld(TldScanner.java:275)
        at org.apache.jasper.servlet.TldScanner$TldScannerCallback.scan(TldScanner.java:315)
        at org.apache.tomcat.util.scan.StandardJarScanner.process(StandardJarScanner.java:391)
        at org.apache.tomcat.util.scan.StandardJarScanner.scan(StandardJarScanner.java:196)
        at org.apache.jasper.servlet.TldScanner.scanJars(TldScanner.java:262)
        at org.apache.jasper.servlet.TldScanner.scan(TldScanner.java:104)
        at org.apache.jasper.servlet.JasperInitializer.onStartup(JasperInitializer.java:83)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4904)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
        ... 38 more
Caused by: java.lang.ClassNotFoundException: oracle.i18n.util.LocaleMapper
        at java.net.URLClassLoader.findClass(URLClassLoader.java:387)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
        ... 54 more
Fri Apr 05 13:19:46 CDT 2024 - 1 - INFO - null - null - null - org.apache.catalina.startup.HostConfig.deployDirectory - Deployment of web application directory [/u01/flexdeploy/apache-tomcat-flexdeploy/webapps/flexdeploy] has finished in [10,051] ms
Fri Apr 05 13:19:46 CDT 2024 - 1 - INFO - null - null - null - org.apache.coyote.AbstractProtocol.start - Starting ProtocolHandler ["http-nio-8000"]
Fri Apr 05 13:19:46 CDT 2024 - 1 - INFO - null - null - null - org.apache.catalina.startup.Catalina.start - Server startup in [12039] milliseconds
Fri Apr 05 13:29:52 CDT 2024 - 13 - WARNING - null - null - null - org.apache.catalina.authenticator.jaspic.PersistentProviderRegistrations.loadProviders - Exception configuring JASPIC to permit java encoding names in XML configuration files. Only IANA encoding names will be supported.
org.xml.sax.SAXNotRecognizedException: SAX feature 'http://apache.org/xml/features/allow-java-encodings' not recognized.
        at oracle.xml.jaxp.JXSAXParserFactory.setFeature(JXSAXParserFactory.java:260)
        at org.apache.tomcat.util.digester.Digester.setFeature(Digester.java:599)
        at org.apache.catalina.authenticator.jaspic.PersistentProviderRegistrations.loadProviders(PersistentProviderRegistrations.java:62)
        at org.apache.catalina.authenticator.jaspic.AuthConfigFactoryImpl.loadPersistentRegistrations(AuthConfigFactoryImpl.java:328)
        at org.apache.catalina.authenticator.jaspic.AuthConfigFactoryImpl.<init>(AuthConfigFactoryImpl.java:63)
        at javax.security.auth.message.config.AuthConfigFactory.lambda$getFactory$0(AuthConfigFactory.java:68)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.message.config.AuthConfigFactory.getFactory(AuthConfigFactory.java:62)
        at org.apache.catalina.authenticator.AuthenticatorBase.findJaspicProvider(AuthenticatorBase.java:1263)
        at org.apache.catalina.authenticator.AuthenticatorBase.getJaspicProvider(AuthenticatorBase.java:1256)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:130)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93)
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:670)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:346)
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:390)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:928)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1786)
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
        at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
        at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(T