title: Wordpress 4.8 - ReferenceError: Can't find variable: wp
body: <p>After updating to Wordpress 4.8 widgets stop working, I mean the textarea inside has disappeared and I read the following error in console:</p>
  
  <pre><code>ReferenceError: Can't find variable: wp
  Global Code — widgets.php:202
  </code></pre>
  
  <p>Looking into the file I see the line causing the issue:</p>
  
  <pre><code>wp.mediaWidgets.init();
  </code></pre>
  
  <p>and so on. There are other blocks related to the <code>wp</code> variable but I really cannot understand why it's happening considering that I've already tried to disable all plugins without success. Any advice?</p>
  
  <p>Thanks.</p>