title: Cannot upgrade Carbon 1 to Carbon 2
body: <p>I've been working on a Laravel project. When I run composer command, I always got warned,</p>
  
  <blockquote>
    <p>Carbon 1 is deprecated, see how to migrate to Carbon 2.
    <a href="https://carbon.nesbot.com/docs/#api-carbon-2" rel="noreferrer">https://carbon.nesbot.com/docs/#api-carbon-2</a>
        You can run './vendor/bin/upgrade-carbon' to get help in updating carbon and other frameworks and libraries that depend on it.</p>
  </blockquote>
  
  <p>Then I run the <strong>./vendor/bin/upgrade-carbon</strong> but I got error,</p>
  
  <blockquote>
    <p>Uncaught Error: Class 'Composer\Composer' not found in .../vendor/nesbot/carbon/src/Carbon/Upgrade.php:131</p>
  </blockquote>
  
  <p>I have also try to search for solutions but it cant be found.
  I really need help to continue my project. Thanks a lot.</p>