title: PHP Error "Unknown: failed to open stream... in Unknown on line 0..." when editing php files
body: <p>I get a strange php error:</p>
  <pre><code>2022-03-14 10:52:19: (mod_fastcgi.c.421) FastCGI-stderr: PHP message: 
  PHP Warning:  Unknown: failed to open stream: 
  No such file or directory in Unknown on line 0
  PHP message: PHP Fatal error:  Unknown: Failed opening required 
  'var/www/vhosts/webdev/sites/test/hello.php'
  (include_path='.') in Unknown on line 0
  </code></pre>
  <p><strong>Long explanation:</strong></p>
  <ol>
  <li><p>I create a file hello.php in my webroot, having the content:</p>
  <p><code>&lt;?php echo(&quot;hello&quot;); ?&gt;</code></p>
  </li>
  <li><p>I run this file in a browser, all is fine, it shows &quot;hello&quot;</p>
  </li>
  <li><p>Now I <em>edit</em> this file so the content now is:</p>
  <p><code>&lt;?php echo(&quot;hello&quot;); echo(&quot;world&quot;); ?&gt;</code></p>
  </li>
  <li><p>I run this edited file in a browser =&gt; The error is shown</p>
  </li>
  <li><p>I reload the page (F5 or ctrl-R) =&gt; all is working fine now</p>
  </li>
  </ol>
  <p><strong>In other words:</strong>
  Whenever I <strong>edit</strong> a php file and try to run it in a browser, I get this error message. After reloading the page it works!</p>
  <p><em>That is the real strange thing, after reloading everything is working fine!!!</em></p>
  <p><strong>My config</strong></p>
  <ul>
  <li><p>a local raspberry pi running raspbian</p>
  </li>
  <li><p>webserver: lighttpd (standard install from repo)</p>
  </li>
  <li><p>php7.3-fpm (standard install from repo)</p>
  </li>
  <li><p>all file permissions in my web dev folder are 775, all files are www-data:www-data owned</p>
  </li>
  <li><p>NO selinux running (like in other answers suggested)</p>
  </li>
  <li><p>the php.ini is pretty much untouched, some options:</p>
   <pre>auto_prepend_file = 
   auto_append_file = 
   include_path = "."</pre>
  </li>
  <li><p>there are no other hidden config files in the folder</p>
  </li>
  </ul>
  <p>With html files there are no problems. So it must be a php-fpm problem.
  I am out of ideas now. It might be a very easy fix, but I am not a Pro.</p>
  <p>Any ideas how to fix this?</p>