title: "Could not find main method from given launch configuration" error when exporting jar from Eclipse
body: <p>I developed my program using Eclipse as my IDE. I used to use <code>File|Export| Runnable JAR file</code> option for creating dist build for client.</p>
  
  <p>I was working with project using Run or (often) Debug button in eclipse (so I have configuration for project with valid main method).</p>
  
  <p>Unfortunately when I created build yesterday I had following error when I tried to run app:</p>
  
  <pre><code>Failed to load Main-Class manifest attribute from My.jar
  </code></pre>
  
  <p>Then when I retried exporting I found the following problem in export log:</p>
  
  <pre><code>Could not find main method from given launch configuration
  </code></pre>
  
  <p>I have no idea what could cause this problem. I think I hadn't change anything in my project configuration. And I'm test my builds so I'm sure this option used to work correctly.</p>
  
  <p>I will appreciate any help.</p>