title: express and fetch: TypeError: NetworkError when attempting to fetch resource
body: <p>I am using express, fetch and firefox.
  This is the code</p>
  <pre><code>async updateTutorial() {
  const requestOptions = {
          method: &quot;POST&quot;,
          headers: { &quot;Content-Type&quot;: &quot;application/json&quot; },
          body: JSON.stringify(this.currentTutorial)
      };
  
    await fetch(&quot;https://localhost:9000/tutorial/update&quot; , requestOptions);
  
  
  }
  </code></pre>
  <p>In Firefox I see this error: TypeError: NetworkError when attempting to fetch resource
  I do not know what kind of problem it is.</p>