title: how to exchange code to token in Ory Hydra
body: <p>I'm following <a href="https://www.ory.sh/hydra/docs/5min-tutorial/" rel="nofollow noreferrer">Ory Hydra 5 Minute Tutorial</a>.</p>
  <p>This tutorial uses a sample Webapp and I'm trying to understand the flow how to convert Code to Token via HTTP POST.</p>
  <p>I have several troubles with the POST:<br />
  <code>400 Bad Request Request parameter 'grant_type' is missing</code><br />
  <code>400 Bad Request &quot;invalid_grant&quot;</code><br />
  <code>401 Unauthorized &quot;invalid_client&quot;</code></p>
  <p>and it's not clear how to proceed.</p>