title: java.lang.ClassNotFoundException: HttpServletRequest
body: <p>I was using Tomcat v8.0.15 on Eclipse Luna, it was working fine. Later, I installed Netbeans; which automatically installed another instance of Tomcat. I deleted one of them. In the result, tomcat stopped working on Eclipse; whenever I try to start tomcat, this error appears: </p>
  
  <pre><code>Caused by: java.lang.NoClassDefFoundError: HttpServletRequest
      at java.lang.Class.getDeclaredMethods0(Native Method)
      at java.lang.Class.privateGetDeclaredMethods(Class.java:2693)
      at java.lang.Class.getDeclaredMethods(Class.java:1967)
      at org.apache.catalina.util.Introspection.getDeclaredMethods(Introspection.java:127)
      at org.apache.catalina.startup.WebAnnotationSet.loadMethodsAnnotation(WebAnnotationSet.java:273)
      at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:133)
      at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:65)
      at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:334)
      at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:774)
      at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:305)
      at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
      at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
      at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5095)
      at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
      ... 6 more
  Caused by: java.lang.ClassNotFoundException: HttpServletRequest
      at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1295)
      at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1147)
      ... 20 more
  </code></pre>