title: PHP require and require_once fails on relative path
body: <p>We have moved our hosting from server which hosted <code>PHP 5.6</code> to a new server which hosts <code>PHP 7.0.</code> After the migration, we've noticed the following issue:</p>
  
  <blockquote>
    <p>PHP Warning: include_once(../classes/ClassA.php): failed to open stream: No such file or directory in /var/www/html/addons/addon.php php on line 37</p>
  </blockquote>
  
  <p>I understand it should work with </p>
  
  <pre><code>include_once __DIR__."/../classes/ClassA.php";
  </code></pre>
  
  <p>But I don't understand why it worked on previous server and not on new one. Are there any <code>php.ini</code> changes that were allowing it to work without __DIR __ prefix? </p>