Class not found exception after upgrade from v7.1 to v7.9

Problem: 

You might be getting this specific pair of exceptions after upgrading from v7.1 to v7.9.

16-Nov-2021 17:43:51.707 INFO [localhost-startStop-1] org.apache.catalina.core.ApplicationContext.log 1 Spring WebApplicationInitializers detected onclasspath
16-Nov-2021 17:43:51.729 SEVERE [localhost-startStop-1] org.apache.catalina.core.StandardContext.listenerStart Error configuring application listenerof class [com.jaspersoft.ji.adhoc.service.AdhocTempARUKiller]
 java.lang.ClassNotFoundException: com.jaspersoft.ji.adhoc.service.AdhocTempARUKiller
        at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1328)
        at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1156)
        at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:546)
        at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:527)
        at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:150)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4714)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5256)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:754)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:730)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
        at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1140)
        at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1875)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

16-Nov-2021 17:43:51.732 SEVERE [localhost-startStop-1] org.apache.catalina.core.StandardContext.listenerStart Error configuring application listenerof class [org.springframework.web.util.Log4jConfigListener]
 java.lang.ClassNotFoundException: org.springframework.web.util.Log4jConfigListener
        at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1328)
        at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1156)
        at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:546)
        at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:527)
        at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:150)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4714)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5256)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:754)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:730)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
        at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1140)
        at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1875)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

16-Nov-2021 17:43:51.773 SEVERE [localhost-startStop-1] org.apache.catalina.core.StandardContext.listenerStart Skipped installing application listeners due to previous error(s)

Solution:

This pair of exceptions is a likely a result of using web.xml from v7.1 on v7.9.   If you have customizations, be sure to start with the correct configuration file for the new version and add your customizations instead of just copying the configuration file from a previous version.  Sometimes it could work, but sometimes configuration file structure is changed from one version to another.