If you are deploying application on Tomcat, JBOSS, or IBM and following error is displayed when you call the application:

SEVERE: Error deploying web application archive MyApplication.war
java.lang.UnsupportedClassVersionError: (com/siperian/lookup/processor/FindTaskProcessor) bad major version at offset=6 (unable to load class com.siperian.lookup.processor.FindTaskProcessor)
    at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2822)
    at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1159)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1647)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
    at org.apache.catalina.startup.WebAnnotationSet.loadClassAnnotation(WebAnnotationSet.java:145)
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationListenerAnnotations(WebAnnotationSet.java:73)
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:56)
    at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:297)
    at org.apache.catalina.startup.ContextConfig.start(ContextConfig.java:1078)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:261)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4612)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
    at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:943)
    at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:778)
    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:504)
    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
    at org.apache.catalina.core.StandardService.start(StandardService.java:525)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:618)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)

This error comes when you have compiled the application with Java 1.6 but running it on Java 1.5. So in order to solve this you can either have Java 1.6 as run time environment in your web server. Or you can re-compile code in Java 1.5 and redeploy it.