title: CKFinder3 Invalid Request Error
body: <p>Hellow everyone!
  I want to use the CKFinder 3 PHP version.</p>
  
  <p>I download the CKFinder zip file from official website.</p>
  
  <p>Then i install XAMPP 7.2.4 to deploy the CKFinder.
  <a href="https://i.stack.imgur.com/gs9QO.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gs9QO.jpg" alt="enter image description here"></a></p>
  
  <p>I start the Apache Web Server at port 80.</p>
  
  <p>Then i copy the CKFinder files to /XAMPP/htdocs/
  <a href="https://i.stack.imgur.com/GheVP.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GheVP.jpg" alt="enter image description here"></a></p>
  
  <p>In order to ensure the PHP environment is correct，I follow the official website to create a test.php which include these code:
  <a href="https://i.stack.imgur.com/jNBfL.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jNBfL.jpg" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/8ErmI.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8ErmI.jpg" alt="enter image description here"></a></p>
  
  <p>And i also follow the offecial website to update <code>config.php</code> file:</p>
  
  <pre><code>$config['authentication'] = function () {
  return true;
  };
  </code></pre>
  
  <p>Now everything is ok, But when I try to access the ckfinder.html at <code>http://localhost/ckfinder/ckfinder.html</code>, some error occured.
  <a href="https://i.stack.imgur.com/BjNK5.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BjNK5.jpg" alt="enter image description here"></a></p>
  
  <p>i can see error log :</p>
  
  <pre><code>[04-May-2018 10:29:57 Europe/Berlin] PHP Fatal error:  Uncaught CKSource\CKFinder\Exception\InvalidConfigException:
   The temporary folder is not writable for CKFinder in 
   /Applications/XAMPP/xamppfiles/htdocs/ckfinder/core/connector/php/vendor/cksource/ckfinder/src/CKSource/CKFinder/Config.php:331
  </code></pre>