title: Magento 2 Controller Post throwing 404 error
body: <p>I've hit an issue trying to add a new action to an existing route in Magento 2.</p>
  <p>I've created a new module, registered it and created a new action extending the existing add to cart functionality. I had this working on an existing project, but had to port it over to a new installation. Now when I attempt to <code>POST</code> to the path: <code>&lt;magentourl&gt;/checkout/cart/addbulk</code>, it throws a <code>404</code>. A <code>GET</code> request will hit the execute method and creates the log entry.</p>
  <p>The following are the components of the module.</p>
  <p><code>app/code/Test/Checkout/etc/module.xml</code></p>
  <pre class="lang-xml prettyprint-override"><code>&lt;?xml version=&quot;1.0&quot;?&gt;
  &lt;config xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot; xsi:noNamespaceSchemaLocation=&quot;urn:magento:framework:Module/etc/module.xsd&quot;&gt;
      &lt;module name=&quot;Test_Checkout&quot; schema_version=&quot;2.0.0&quot; setup_version=&quot;2.0.3&quot;&gt;
          &lt;sequence&gt;
              &lt;module name=&quot;Magento_Checkout&quot;/&gt;
          &lt;/sequence&gt;
      &lt;/module&gt;
  &lt;/config&gt;
  </code></pre>
  <p><code>app/code/Test/Checkout/etc/frontend/routes.xml</code></p>
  <pre class="lang-xml prettyprint-override"><code>&lt;?xml version=&quot;1.0&quot;?&gt;
  &lt;config xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot; xsi:noNamespaceSchemaLocation=&quot;urn:magento:framework:App/etc/routes.xsd&quot;&gt;
      &lt;router id=&quot;standard&quot;&gt;
          &lt;route id=&quot;checkout&quot; frontName=&quot;checkout&quot;&gt;
              &lt;module name=&quot;Test_Checkout&quot; /&gt;
          &lt;/route&gt;
      &lt;/router&gt;
  &lt;/config&gt;
  </code></pre>
  <p><code>app/code/Test/Checkout/Controller/Cart/Addbulk.php</code></p>
  <pre class="lang-php prettyprint-override"><code>&lt;?php
  namespace Test\Checkout\Controller\Cart;
  
  class Addbulk extends \Magento\Checkout\Controller\Cart\Add
  {
      
      public function execute()
      {
          $items = $this-&gt;getRequest()-&gt;getParam('item', []);
          $this-&gt;_objectManager-&gt;get('Psr\Log\LoggerInterface')&gt;addDebug('Posting data to addBulk');
          
          ...
  
          return $this-&gt;_goBack();
      }
  }
  </code></pre>
  <p>I've enabled the module, run <code>bin/magento setup:upgrade</code>, cleared cache and then attempted to post.
  When I do a <code>POST</code>, it returns a <code>404</code> error, on a <code>GET</code> it creates the log entry as expected.</p>
  <p>Does anyone have any idea why this module would not have migrated correctly, or anything else I would need to add to get this working?</p>