title: JSF 1.2- >2.0 :viewId parameter for save view state is null
body: <p>We are migrating our JSF 1.2 project to JSF 2.0  and using a command button in a JSP page .Clicking command button get a reponse from external system and display response.</p>
  
  <p>While clicking this command button we are getting blank page with below execption</p>
  
  <p>During debug I found that we are getting a success response but its not able to find original page as it lost state view ID</p>
  
  <pre><code>[8/13/13 11:01:30:538 CDT] 000000e0 webapp        E com.ibm.ws.webcontainer.webapp.WebApp logServletError SRVE0293E: [Servlet Error]-[Faces Servlet]: java.lang.NullPointerException: viewId parameter for  save view state is null
      at org.ajax4jsf.application.AjaxStateHolder.saveState(AjaxStateHolder.java:155)
      at org.ajax4jsf.application.AjaxStateManager.saveStateInSession(AjaxStateManager.java:523)
      at org.ajax4jsf.application.AjaxStateManager.buildViewState(AjaxStateManager.java:503)
      at org.ajax4jsf.application.AjaxStateManager.saveView(AjaxStateManager.java:462)
      at org.apache.myfaces.shared_impl.view.JspViewDeclarationLanguageBase.renderView(JspViewDeclarationLanguageBase.java:206)
      at org.apache.myfaces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:263)
      at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:59)
      at org.apache.myfaces.tomahawk.application.ResourceViewHandlerWrapper.renderView(ResourceViewHandlerWrapper.java:169)
      at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100)
      at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:176)
  </code></pre>
  
  <p>Is there any specific config required in web.xml to save view state ?</p>