title: Eclipse cannot rename or delete file
body: <p>In error log:</p>
  
  <pre><code>...
  Caused by: java.lang.NoClassDefFoundError:  org/eclipse/jpt/common/utility/internal/StatefulCommandExecutor
  ...
  Caused by: java.lang.ClassNotFoundException: org.eclipse.jpt.common.utility.internal.StatefulCommandExecutor
  ...
  </code></pre>
  
  <p>Which package does this belong to? How could I reinstall this package ? </p>
  
  <p>EDIT:
  Preference->Run/Debug->Launching->Default Launchers. It's empty there. The Launch Type and it's Preferred Launcher column is empty. Is it normal? If this is causing the problem. How can I fix it? </p>