title: Uncaught (in promise) TypeError: Failed to execute 'Cache' on 'addAll': Request failed on progressive web app
body: <p>I am following a simple PWA tutorial, but when I complete it I get the following console error,</p>
  <p><code>Uncaught (in promise) TypeError: Failed to execute 'Cache' on 'addAll': Request failed</code></p>
  <p>Here is my serviceworker file</p>
  <pre><code>const staticDevCoffee = &quot;dev-coffee-site-v1&quot;
  const assets = [
    &quot;/&quot;,
    &quot;/test.html&quot;,
    &quot;/csstest/style.css&quot;,
    &quot;/jstest/app.js&quot;,
    &quot;/coffee.png&quot;,
  ]
  
  self.addEventListener(&quot;install&quot;, installEvent =&gt; {
    installEvent.waitUntil(
      caches.open(staticDevCoffee).then(cache =&gt; {
        cache.addAll(assets)
      })
    )
  })
  </code></pre>
  <p>When I run lighthouse tests, I get this,</p>
  <pre><code>start_url does not respond with a 200 when offlineThe start_url did respond, but not via a service worker.
  </code></pre>
  <p>This is my first look at PWAs so I am a little stuck. I have tried several solutions I have found on SO, but none work.</p>