title: Reference - Composer error "Your PHP version does not satisfy requirements" after upgrading PHP
body: <p>After updating PHP from 7.4 to 8.0, I ran <code>composer update</code> on my existing project, and got an error like this:</p>
  <blockquote>
  <ul>
  <li>acme/some-package[1.0.0, ..., 1.4.0] requires php ^5.6.4 || ^7.0 -&gt; your php version (8.0.3) does not satisfy that requirement.</li>
  </ul>
  </blockquote>
  <p>What does this mean, and how do I fix it?</p>
  <p><em>(This is a reference answer intended to cover a frequently encountered issue. The scenario is just an example. See also: &quot;<a href="https://stackoverflow.com/questions/48073506/how-to-explain-composers-error-log">How to explain Composer&#39;s error log?</a>&quot;)</em></p>