title: No Application Encryption Key Has Been Specified
body: <p>I'm new to Laravel and I'm trying to use the Artisan command...</p>
  
  <pre><code>php artisan serve
  </code></pre>
  
  <p>It displays...</p>
  
  <blockquote>
    <p>Laravel development server started: <a href="http://127.0.0.1:8000" rel="noreferrer">http://127.0.0.1:8000</a></p>
  </blockquote>
  
  <p>However, it won't automatically launch and when I manually enter <a href="http://127.0.0.1:8000" rel="noreferrer">http://127.0.0.1:8000</a> it shows this error:</p>
  
  <blockquote>
    <p>RuntimeException No application encryption key has been specified.</p>
  </blockquote>
  
  <p>Any ideas? I'm using Laravel framework 5.5-dev.</p>