title: How do I resolve "PHP Fatal error: Unknown: Failed opening required"
body: <p>I have two sites on a LAMP stack. One (Site1) uses WordPress with Wordfence, and it works perfectly fine. The second website (Site2) only runs a simple index.php file on it:</p>
  
  <pre><code>&lt;?php
  echo "Testing";
  ?&gt;
  </code></pre>
  
  <p>However, it shows HTTP ERROR 500 with the error log as below. </p>
  
  <pre><code>[Thu Dec 22 16:23:44.774993 2016] [:error] [pid 56607] [client xxx:27253] PHP Warning:  Unknown: failed to open stream: No such file or directory in Unknown on line 0
  [Thu Dec 22 16:23:44.775042 2016] [:error] [pid 56607] [client xxx:27253] PHP Fatal error:  Unknown: Failed opening required '/var/www/site1/public_html/public/wordfence-waf.php' (include_path='.:/usr/share/php') in Unknown on line 0
  </code></pre>
  
  <p>Site1 and Site2 have nothing to do with each other, and they are located in separate folders. I am not sure what's happening. Please advise. </p>
  
  <p><em>.htaccess</em> file on Site1</p>
  
  <pre><code># BEGIN WordPress
  &lt;IfModule mod_rewrite.c&gt;
  RewriteEngine On
  RewriteBase /
  RewriteRule ^index\.php$ - [L]
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule . /index.php [L]
  &lt;/IfModule&gt;
  
  # END WordPress
  
  # Wordfence WAF
  &lt;IfModule mod_php7.c&gt;
          php_value auto_prepend_file '/var/www/site1/public_html/public/wordfence-waf.php'
  &lt;/IfModule&gt;
  &lt;Files ".user.ini"&gt;
  &lt;IfModule mod_authz_core.c&gt;
          Require all denied
  &lt;/IfModule&gt;
  &lt;IfModule !mod_authz_core.c&gt;
          Order deny,allow
          Deny from all
  &lt;/IfModule&gt;
  &lt;/Files&gt;
  
  # END Wordfence WAF
  </code></pre>