title: http 503 error gwt jetty server SERVICE_UNAVAILABLE
body: <p>i get 503 error from eclipse integrated jetty server while running project in a web browser. i get this error since i changed the gae application-id of the project.</p>
  
  <pre><code>java.lang.ClassNotFoundException: com.google.api.server.spi.SystemServiceServlet
  at java.net.URLClassLoader$1.run(Unknown Source)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(Unknown Source)
  at java.lang.ClassLoader.loadClass(Unknown Source)
  at com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:176)
  at java.lang.ClassLoader.loadClass(Unknown Source)
  at org.mortbay.util.Loader.loadClass(Loader.java:91)
  at org.mortbay.util.Loader.loadClass(Loader.java:71)
  at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
  at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
  at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
  at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
  at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
  at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
  at org.mortbay.jetty.Server.doStart(Server.java:224)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at com.google.appengine.tools.development.JettyContainerService.startContainer(JettyContainerService.java:191)
  at com.google.appengine.tools.development.AbstractContainerService.startup(AbstractContainerService.java:239)
  at com.google.appengine.tools.development.DevAppServerImpl.start(DevAppServerImpl.java:146)
  at com.google.appengine.tools.development.gwt.AppEngineLauncher.start(AppEngineLauncher.java:97)
  at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:509)
  at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1068)
  at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:811)
  at com.google.gwt.dev.DevMode.main(DevMode.java:311)
      21.08.2012 16:09:42 com.google.appengine.tools.development.ApiProxyLocalImpl log
      SCHWERWIEGEND: javax.servlet.ServletContext log: unavailable
      javax.servlet.UnavailableException: com.google.api.server.spi.SystemServiceServlet
  at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:79)
  at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
  at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
  at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
  at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
  at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
  at org.mortbay.jetty.Server.doStart(Server.java:224)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at   com.google.appengine.tools.development.JettyContainerService.startContainer(JettyContainerS ervice.java:191)
  at com.google.appengine.tools.development.AbstractContainerService.startup(AbstractContainerService.java:239)
  at com.google.appengine.tools.development.DevAppServerImpl.start(DevAppServerImpl.java:146)
  at com.google.appengine.tools.development.gwt.AppEngineLauncher.start(AppEngineLauncher.java:97)
  at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:509)
  at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1068)
  at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:811)
  at com.google.gwt.dev.DevMode.main(DevMode.java:311)
  
      21.08.2012 16:09:42 com.google.apphosting.utils.jetty.JettyLogger warn
      WARNUNG: failed SystemServiceServlet: java.lang.NullPointerException
      21.08.2012 16:09:43 com.google.apphosting.utils.jetty.JettyLogger warn
      WARNUNG: Failed startup of context    com.google.appengine.tools.development.DevAppEngineWebAppContext@9f4160a{/,C:\Users\dp\work        space\fooApp\war}
      java.lang.NullPointerException
       at java.lang.Class.isAssignableFrom(Native Method)
  at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:256)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
  at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
  at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
  at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
  at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
  at org.mortbay.jetty.Server.doStart(Server.java:224)
  at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
  at com.google.appengine.tools.development.JettyContainerService.startContainer(JettyContainerService.java:191)
  at com.google.appengine.tools.development.AbstractContainerService.startup(AbstractContainerService.java:239)
  at com.google.appengine.tools.development.DevAppServerImpl.start(DevAppServerImpl.java:146)
  at com.google.appengine.tools.development.gwt.AppEngineLauncher.start(AppEngineLauncher.java:97)
  at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:509)
  at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1068)
  at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:811)
  at com.google.gwt.dev.DevMode.main(DevMode.java:311)
      21.08.2012 16:09:46 com.google.appengine.tools.development.DevAppServerImpl start
      INFO: The server is running at http://localhost:8888/
      21.08.2012 16:09:46 com.google.appengine.tools.development.DevAppServerImpl start
      INFO: The admin console is running at http://localhost:8888/_ah/admin
  </code></pre>
  
  <p>this is my web.xml file</p>
  
  <pre><code>&lt;!-- Default page to serve --&gt;
  &lt;welcome-file-list&gt;
     &lt;welcome-file&gt;fooApp.html&lt;/welcome-file&gt;
  &lt;/welcome-file-list&gt;
  &lt;servlet&gt;
     &lt;servlet-name&gt;phonegapfileapi&lt;/servlet-name&gt;
     &lt;servlet           class&gt;com.googlecode.gwtphonegap.server.file.FileRemoteServiceServlet&lt;/servlet-class&gt;
     &lt;/servlet&gt;
     &lt;servlet-mapping&gt;
        &lt;servlet-name&gt;phonegapfileapi&lt;/servlet-name&gt;
        &lt;url-pattern&gt;/showcase/phonegapfileapi&lt;/url-pattern&gt;
     &lt;/servlet-mapping&gt;
     &lt;servlet&gt;
         &lt;servlet-name&gt;SystemServiceServlet&lt;/servlet-name&gt;
         &lt;servlet-class&gt;com.google.api.server.spi.SystemServiceServlet&lt;/servlet-class&gt;
         &lt;init-param&gt;
            &lt;param-name&gt;services&lt;/param-name&gt;
         &lt;param-value/&gt;
       &lt;/init-param&gt;
     &lt;/servlet&gt;
  
     &lt;servlet-mapping&gt;
        &lt;servlet-name&gt;SystemServiceServlet&lt;/servlet-name&gt;
        &lt;url-pattern&gt;/_ah/spi/*&lt;/url-pattern&gt;
     &lt;/servlet-mapping&gt;
  </code></pre>
  
  <p>all jars are in fooApp/war/WEB-INF/lib
  how could i solve this problem?
  please help.</p>