title: Issue while upgrading to struts version 2.5.17
body: <p>I am trying to upgrade struts version from 2.3.35 to 2.5.17 but I encountered an issue as below:</p>
  
  <pre><code>java.lang.NullPointerException
      at com.opensymphony.xwork2.util.fs.StrutsJarURLConnection.getInputStream(StrutsJarURLConnection.java:170)
      at com.opensymphony.xwork2.util.fs.JarEntryRevision.needsReloading(JarEntryRevision.java:84)
      at com.opensymphony.xwork2.util.fs.DefaultFileManager.fileNeedsReloading(DefaultFileManager.java:65)
      at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.needsReload(XmlConfigurationProvider.java:428)
      at org.apache.struts2.config.StrutsXmlConfigurationProvider.needsReload(StrutsXmlConfigurationProvider.java:163)
  </code></pre>
  
  <p>I have been using this guide to migrate to struts version 2.5.17:
  <a href="https://cwiki.apache.org/confluence/display/WW/Struts+2.3+to+2.5+migration" rel="nofollow noreferrer">https://cwiki.apache.org/confluence/display/WW/Struts+2.3+to+2.5+migration</a></p>
  
  <p>I suspect it to be issue with tiles.</p>
  
  <p>I have upgraded all struts related jar to version 2.5.17 including struts2-tiles-plugin. I have also upgraded all tiles related jars to 3.0.7.</p>
  
  <p>Also I have removed the Xwork-core jar as from 2.5 xwork being merged to struts2-core jar.</p>
  
  <p>Am I doing anything wrong.</p>
  
  <p>Please note: I have not done any code changes as of now. The code works perfectly with struts version 2.3.35. But as soon as I have upgraded the struts version along with tiles version I started getting this issue.</p>
  
  <p>Can some one please suggest If I am doing anything wrong?</p>