title: Fatal Error: Call to undefined function gzopen() when installing WordPress theme
body: <p>I'm seeing the below error after attempting to activate a WordPress theme.  The error message in the browser is...</p>
  
  <pre><code>Fatal error: Call to undefined function gzopen() in /var/www/mysite.com/wp-content/themes/flat/themify/themify-builder/classes/class-themify-builder-layouts.php on line 528
  </code></pre>
  
  <p>Checking my <code>/var/log/apache2/error.log</code> I see the following error:</p>
  
  <pre><code>Call to undefined function gzopen() in /var/www/mywebsite.com/wp-      content/themes/flat/themify/themify-builder/classes/class-themify-builder-layouts.php on line     528, referer: http://mywebsite.com/wp-admin/update.php?action=upload-theme
  </code></pre>
  
  <p>Server information:</p>
  
  <pre><code>OS: Ubuntu 14.04 LTS
  Apache: APache/2.4.7
  PHP: PHP 5.5.9-1ubuntu4
  </code></pre>