title: Identity Server 4 /connect/token return 400 Bad Request when using grant_type:authorization_code
body: <p>I have setup an Identity Server 4 App. Trying to set an angular client app.
  Able to access provider login page and login successfully, after getting the Authorization code when, angular app calling <code>/connect/token</code> api, getting 400 Bad Request. Tested with Postman, it is working when using</p>
  <pre><code>grant_type:client_credentials
  </code></pre>
  <p>Information</p>
  <p>https://localhost:5001/connect/token</p>
  <pre><code>grant_type:authorization_code
  client_id:angular_app_client_id
  code_verifier:C0.731426161751518815973254dfd6715973254680670.9347059398232558
  code:oSEydAywPs_zg4MRwbqwH-ly8ToWdrtexTDgx0ee7eY
  redirect_uri:http://localhost:4200/callback
  client_secret:&lt;secret&gt;
  require_pkce:false
  requried_client_secret:false
  </code></pre>
  <p>OpenIdConfiguration in angular app</p>
  <pre><code>const openIdConfiguration: OpenIdConfiguration = {
      stsServer: this.authUrl,
      redirect_url: this.originUrl + 'callback',
      client_id: 'demo_client_id',
      response_type: 'code',
      scope: 'openid profile',
      post_logout_redirect_uri: this.originUrl,
      forbidden_route: '/forbidden',
      unauthorized_route: '/unauthorized',
      silent_renew: true,
      silent_renew_url: this.originUrl + '/silent-renew.html',
      history_cleanup_off: true,
      auto_userinfo: true,
      log_console_warning_active: true,
      log_console_debug_active: true,
      max_id_token_iat_offset_allowed_in_seconds: 10,
  };
  </code></pre>
  <p>Postman Request
  <a href="https://i.stack.imgur.com/MtSib.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MtSib.png" alt="enter image description here" /></a></p>
  <p>Server Log</p>
  <pre><code>{&quot;ClientId&quot;: &quot;angular_app_client_id&quot;, &quot;Category&quot;: &quot;Authentication&quot;, &quot;Name&quot;: &quot;Client Authentication Failure&quot;, &quot;EventType&quot;: &quot;Failure&quot;, &quot;Id&quot;: 1011, &quot;Message&quot;: &quot;Invalid client secret&quot;, &quot;ActivityId&quot;: &quot;0HM1VK1OS0MDK:00000001&quot;, &quot;TimeStamp&quot;: &quot;2020-08-13T16:29:52.0000000Z&quot;, &quot;ProcessId&quot;: 2002, &quot;LocalIpAddress&quot;: &quot;::1:5001&quot;, &quot;RemoteIpAddress&quot;: &quot;::1&quot;, &quot;$type&quot;: &quot;ClientAuthenticationFailureEvent&quot;}
  </code></pre>
  <p>Working when grant_type is <code>client_credentials</code>
  <a href="https://i.stack.imgur.com/2RJfh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2RJfh.png" alt="enter image description here" /></a></p>
  <p>Please help...</p>