title: Why am I receiving a 401 Unauthorized error when requesting API data from React?
body: <p>To make a long story short, I'm building a server-rendered Express / React application and I'm trying to query the back-end, from the client, for some data. The basic flow looks like this:</p>
  
  <ol>
  <li>User navigates to a client path <code>applications/:id</code></li>
  <li>The <code>Application</code> component is loaded</li>
  <li>A <code>GET</code> request is made to the server's API from the <code>Application</code> component lifecycle method <code>componentWillMount</code></li>
  <li>The data from the response is added to Redux</li>
  </ol>
  
  <p>The problem is that the response (step 4) is a 401 (Unauthorized). This is not an issue of being logged in or not. A valid session exists and if I navigate to the API route from the browser, I can see the expected response. As an added note, this application is similar to another application (in nearly ever relevant aspect), which does not have this issue.</p>
  
  <p>Attempted troubleshooting steps:</p>
  
  <ol>
  <li>Verified correct modules and versions</li>
  <li>Verified correct API request path and configuration (using Axios and <code>withCredentials</code> config param)</li>
  <li>Verified server routing and authentication</li>
  <li>Verified PassportJS config</li>
  <li>Verified the request session is being lost in the auth process</li>
  </ol>