title: New jenkins server after inital setup - blank screen
body: <p>I have a fairly new installation of Jenkins that was working prior to Christmas, but today when I try to access it I get a blank browser screen. During the intial setup I successfully unlocked the server and verified that everything was working, but did not install any plugins as the server was firewalled. This has since been resolved.</p>
  <p>Requests to http://server-name:8080/ return a blank screen, with the following source code:</p>
  <pre><code>
      &lt;!DOCTYPE html&gt;&lt;html&gt;&lt;head resURL=&quot;/static/9fe70b8e&quot; data-rooturl=&quot;&quot; data-resurl=&quot;/static/9fe70b8e&quot;&gt;
          
      &lt;title&gt;Jenkins [Jenkins]&lt;/title&gt;
      &lt;link rel=&quot;stylesheet&quot; href=&quot;/static/9fe70b8e/css/layout-common.css&quot; type=&quot;text/css&quot; /&gt;
      &lt;link rel=&quot;stylesheet&quot; href=&quot;/static/9fe70b8e/css/style.css&quot; type=&quot;text/css&quot; /&gt;
      &lt;link rel=&quot;stylesheet&quot; href=&quot;/static/9fe70b8e/css/color.css&quot; type=&quot;text/css&quot; /&gt;
      &lt;link rel=&quot;stylesheet&quot; href=&quot;/static/9fe70b8e/css/responsive-grid.css&quot; type=&quot;text/css&quot; /&gt;
      &lt;link rel=&quot;shortcut icon&quot; href=&quot;/static/9fe70b8e/favicon.ico&quot; type=&quot;image/vnd.microsoft.icon&quot; /&gt;
      &lt;link color=&quot;black&quot; rel=&quot;mask-icon&quot; href=&quot;/images/mask-icon.svg&quot; /&gt;
      &lt;script&gt;var isRunAsTest=false; var rootURL=&quot;&quot;; var resURL=&quot;/static/9fe70b8e&quot;;&lt;/script&gt;
      &lt;script src=&quot;/static/9fe70b8e/scripts/prototype.js&quot; type=&quot;text/javascript&quot;&gt;&lt;/script&gt;
      &lt;script src=&quot;/static/9fe70b8e/scripts/behavior.js&quot; type=&quot;text/javascript&quot;&gt;&lt;/script&gt;
      &lt;script src='/adjuncts/9fe70b8e/org/kohsuke/stapler/bind.js' type='text/javascript'&gt;&lt;/script&gt;
  
  </code></pre>
  <p>The latest entry in the jenkins.log file has the following:</p>
  <p>2021-01-06 07:59:38.063+0000 [id=15]    WARNING o.e.jetty.server.HttpChannel#handleException: ERROR dispatch failed
  org.apache.commons.jelly.JellyTagException: jar:file:/var/cache/jenkins/war/WEB-INF/lib/jenkins-core-2.190.3.jar!/lib/layout/view.jelly:42:20: &lt;d:invokeBody&gt; class hudson.security.csrf.DefaultCrumbIssuer is missing its descriptor</p>
  <p>I've tried restarting the server and this didn't change anything. Can anybody provide some pointers (or if this is the wrong place to raise something like this, let me know where I should ask!)</p>
  <p>Cheers,</p>
  <p>Brendan</p>