title: Why Weka snapshot version won't start (or after some library installation)?
body: <p><strong>Problem encountered</strong>     </p>
  
  <p>There are two situations I met when I failed to start weka snapshot version with <code>java -jar weka.jar</code></p>
  
  <ol>
  <li>when I downloaded the snapshot version and start it for the first time     </li>
  <li>after I have installed a new weka library, and start snapshot again from terminal</li>
  </ol>
  
  <p>I have found error messages as below:</p>
  
  <pre><code>Exception in thread "main" java.lang.InternalError: Failed to invoke main method
      weka.gui.SplashWindow.invokeMain(SplashWindow.java:308)
      weka.gui.GUIChooser.main(GUIChooser.java:92)
  
      at weka.gui.SplashWindow.invokeMain(SplashWindow.java:308)
      at weka.gui.GUIChooser.main(GUIChooser.java:92)
  Caused by: java.lang.reflect.InvocationTargetException
      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:497)
      at weka.gui.SplashWindow.invokeMain(SplashWindow.java:305)
      ... 1 more
  Caused by: java.lang.VerifyError: Bad access to protected data in invokevirtual
  Exception Details:
    Location:
      weka/filters/MakePreconstructedFilter.setConstructed()V @11: invokevirtual
    Reason:
      Type 'weka/filters/Filter' (current frame, stack[0]) is not assignable to 'weka/filters/MakePreconstructedFilter'
    Current Frame:
      bci: @11
      flags: { }
      locals: { 'weka/filters/MakePreconstructedFilter' }
      stack: { 'weka/filters/Filter' }
    Bytecode:
      0x0000000: 2ab6 0021 c600 122a b600 21b6 0023 c600
      0x0000010: 082a 03b5 0002 b1                      
    Stackmap Table:
      same_frame(@22)
  
      at java.lang.Class.forName0(Native Method)
      at java.lang.Class.forName(Class.java:348)
      at weka.core.WekaPackageClassLoaderManager.forName(WekaPackageClassLoaderManager.java:198)
      at weka.core.WekaPackageClassLoaderManager.forName(WekaPackageClassLoaderManager.java:178)
      at weka.core.ClassDiscovery.find(ClassDiscovery.java:351)
      at weka.gui.GenericPropertiesCreator.generateOutputProperties(GenericPropertiesCreator.java:541)
      at weka.gui.GenericPropertiesCreator.execute(GenericPropertiesCreator.java:638)
      at weka.gui.GenericPropertiesCreator.execute(GenericPropertiesCreator.java:614)
      at weka.core.converters.ConverterUtils.initialize(ConverterUtils.java:748)
      at weka.core.converters.ConverterUtils.&lt;clinit&gt;(ConverterUtils.java:729)
      at java.lang.Class.forName0(Native Method)
      at java.lang.Class.forName(Class.java:348)
      at weka.core.WekaPackageClassLoaderManager.forName(WekaPackageClassLoaderManager.java:198)
      at weka.core.WekaPackageClassLoaderManager.forName(WekaPackageClassLoaderManager.java:178)
      at weka.core.ClassDiscovery.find(ClassDiscovery.java:351)
      at weka.gui.GenericPropertiesCreator.generateOutputProperties(GenericPropertiesCreator.java:541)
      at weka.gui.GenericPropertiesCreator.execute(GenericPropertiesCreator.java:638)
      at weka.gui.GenericPropertiesCreator.&lt;clinit&gt;(GenericPropertiesCreator.java:166)
      at weka.core.WekaPackageManager.processGenericPropertiesCreatorProps(WekaPackageManager.java:587)
      at weka.core.WekaPackageManager.loadPackages(WekaPackageManager.java:1196)
      at weka.core.WekaPackageManager.loadPackages(WekaPackageManager.java:1091)
      at weka.gui.GenericObjectEditor.determineClasses(GenericObjectEditor.java:192)
      at weka.gui.GenericObjectEditor.&lt;clinit&gt;(GenericObjectEditor.java:262)
      at weka.gui.GUIChooserApp.&lt;init&gt;(GUIChooserApp.java:748)
      at weka.gui.GUIChooserApp.createSingleton(GUIChooserApp.java:261)
      at weka.gui.GUIChooserApp.main(GUIChooserApp.java:1816)
      ... 6 more
  </code></pre>