title: Extension installed from Chrome Webstore throws error "Package is invalid. Details: 'Cannot load extension with file or directory name _metadata...'
body: <p>When a CRX is added to the Chrome web store, Google adds a directory <code>_metadata</code> to the crx. Older versions of Chrome do not know about this directory (tested on Chrome 27) and throw this error:</p>
  
  <pre><code>Package is invalid. Details: 'Cannot load extension with file or directory name
  _metadata. Filenames starting with "_" are reserved for use by the system.'.
  </code></pre>
  
  <p>You can see this error if you try to install this extension on an older version of Chrome: <a href="https://chrome.google.com/webstore/detail/allcast-receiver/hjbljnpdahefgnopeohlaeohgkiidnoe">https://chrome.google.com/webstore/detail/allcast-receiver/hjbljnpdahefgnopeohlaeohgkiidnoe</a></p>
  
  <p>A good explanation: <a href="https://groups.google.com/a/chromium.org/d/msg/chromium-apps/huDqSeaQx3Q/Z5GOMxA7lQIJ">https://groups.google.com/a/chromium.org/d/msg/chromium-apps/huDqSeaQx3Q/Z5GOMxA7lQIJ</a></p>
  
  <p>Is there a workaround for this? This makes it impossible to support older versions of Chrome.</p>