title: Troubleshooting Identity Server 4
body: <p>I am using Identity Server 4 for authentication. I have MVC client. Few days ago i was able to authenticate successfully. But recently i made some changes in Identity Server project which broke something. I am getting</p>
  
  <blockquote>
    <p>unauthorized_client The client application is not known or is not authorized.</p>
  </blockquote>
  
  <p>I tried all the possible fixes but couldn't fix it. Is there any way i can debug the code. I could see that the call was made to <code>/connect/authorize</code> endpoint and calls are going to <code>IScopeStore.FindScopesAsync</code> and <code>IClientStore.FindClientByIdAsync</code> and i verified it has all proper <code>AllowedScopes</code>.  </p>
  
  <p>Can anyone tell me how do i troubleshoot these kind of issues with Identity Server 4. Also, i am interested to know the execution flow. What IDSvr endpoints are called and when?</p>