title: Laravel/Illuminate Fatal Error
body: <p>I got a web app that works on my local computer, but not on my server. I get this error on server. I checked the code that the error mentions about, and there's nothing wrong with it. </p>
  
  <p>Do you have any idea what causes this? </p>
  
  <p>Thank you very much in advance. </p>
  
  <p>Here's my error message: </p>
  
  <pre><code>Fatal error: Interface 'Illuminate\Exception\ExceptionDisplayerInterface' not found in /var/www/test-app.domain.com/public_html/vendor/laravel/framework/src/Illuminate/Exception/SymfonyDisplayer.php on line 6
  </code></pre>
  
  <p>Here's SymphonyDisplayer.php's line 6: </p>
  
  <pre><code>class SymfonyDisplayer implements ExceptionDisplayerInterface {
  </code></pre>
  
  <p>It says that there's no <code>ExceptionDisplayerInterface</code>. However, it's right next to this file, in the same directory. <code>ExceptionDisplayerInterface.php</code> is in <code>Exception</code> folder with <code>SymphonyDisplayer.php</code></p>
  
  <p>Here's my <code>composer install</code> output: </p>
  
  <pre><code>&gt;&gt;composer install
  Loading composer repositories with package information
  Installing dependencies (including require-dev) from lock file
  Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - jeremeamia/SuperClosure 1.0.1 requires nikic/php-parser ~0.9 -&gt; no matching package found.
      - jeremeamia/SuperClosure 1.0.1 requires nikic/php-parser ~0.9 -&gt; no matching package found.
      - Installation request for jeremeamia/superclosure 1.0.1 -&gt; satisfiable by jeremeamia/SuperClosure[1.0.1].
  
  Potential causes:
   - A typo in the package name
   - The package is not available in a stable-enough version according to your minimum-stability setting
     see &lt;https://groups.google.com/d/topic/composer-dev/_g3ASeIFlrc/discussion&gt; for more details.
  
  Read &lt;http://getcomposer.org/doc/articles/troubleshooting.md&gt; for further common problems.
  </code></pre>
  
  <p>Here's a new error after executing <code>composer update</code>:</p>
  
  <pre><code>Fatal error: Interface 'Whoops\Handler\HandlerInterface' not found in /var/www/test-app.domain.com/public_html/vendor/filp/whoops/src/Whoops/Handler/Handler.php on line 17
  </code></pre>
  
  <p>Here's some more outputs while trying to figure out the problem: </p>
  
  <pre><code>&gt;&gt;composer diagnose
  Checking platform settings: OK
  Checking git settings: OK
  Checking http connectivity: OK
  Checking composer.json: OK
  Checking disk free space: OK
  Checking composer version: OK
  &gt;&gt;composer self-update
  You are already using composer version 0d4c2bb7d7a864a9b3e876908e743310cdeaa5e6.
  </code></pre>