title: Cannot sent headers error after SUPEE 6788 patch Magento
body: <p>I'm using a template on my Magento 1.9.1.0 and after patch with SUPEE 6788, I'm getting the following errors in my system.log:</p>
  
  <pre><code>2016-04-26T00:50:23+00:00 DEBUG (7): Cannot send headers; headers already sent in /usr/share/nginx/html/app/code/community/Ves/Tabs/controllers/IndexController.php, line 140
  2016-04-26T00:50:23+00:00 DEBUG (7): HEADERS ALREADY SENT: &lt;pre&gt;[0] /usr/share/nginx/html/app/code/core/Mage/Core/Controller/Response/Http.php:52
  [1] /usr/share/nginx/html/lib/Zend/Controller/Response/Abstract.php:771
  [2] /usr/share/nginx/html/app/code/core/Mage/Core/Controller/Response/Http.php:84
  [3] /usr/share/nginx/html/app/code/core/Mage/Core/Controller/Varien/Front.php:184
  [4] /usr/share/nginx/html/app/code/core/Mage/Core/Model/App.php:354
  [5] /usr/share/nginx/html/app/Mage.php:684
  [6] /usr/share/nginx/html/index.php:87
  </code></pre>
  
  <p>In IndexController.php on line 140, I have this code:</p>
  
  <pre><code>echo Mage::helper('core')-&gt;jsonEncode( $json );
  </code></pre>
  
  <p>I think the way as json is called is causing this errors. How can I fix this?</p>
  
  <p>Thanks in advance.</p>