title: How To Debug HTTP Error 400 in JSP
body: <p>I have the following code that prints some links on the page, and is supposed to call a controller method (launch), upon clicking the image.  However, I am getting an Error 400 when I click the button.  The generated links look correct to me.  The code is in the 1st block.  The actual View-Source is in the 2nd. </p>
  
  <p>Unfortunately, I am not getting any errors in my server logs, so I don't know where to begin to debug this.</p>
  
  <p>Does anyone see anything wrong with my code.</p>
  
  <pre><code>&lt;div id="links"&gt;
      &lt;ul&gt;
          &lt;c:forEach items="${listAppURLForm}" var="appURLForm"&gt;
              &lt;li&gt;
                  &lt;h2&gt;${appURLForm.link}&lt;/h2&gt;
                  &lt;p&gt;
                      &lt;span&gt;
                          &lt;form method="post" action='&lt;c:url value="launch"/&gt;'&gt;
                              &lt;input type="hidden" name="id" value="${appURLForm.link}"/&gt;
                              &lt;input type="image" src='&lt;c:url value="/images/rocket-thumbnail.png"/&gt;'/&gt;
                          &lt;/form&gt;
                      &lt;/span&gt;
                  &lt;/p&gt;
              &lt;/li&gt;
          &lt;/c:forEach&gt;
      &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>The rendered page:</p>
  
  <pre><code>&lt;form method="post" action='launch;jsessionid=40d63cd386e5d01ef8c6dc1c1b76'&gt;
      &lt;input type="hidden" name="id" value="http://www.cnn.com"/&gt;
      &lt;input type="image" src='/services/images/rocket-thumbnail.png;jsessionid=40d63cd386e5d01ef8c6dc1c1b76'/&gt;
   &lt;/form&gt;
  </code></pre>