title: Google colab file download failed to fetch error
body: <p>I used google colab to make a dictionary, dump it into a json file and download the file into my laptop by this code:</p>
  
  <pre><code>from google.colab import files
  import json
  
  dict = {'apple': 'fruit', 'mango': 'fruit', 'carrot': 'vegetable', 'brocoli': 'vegetable', 'cat': 'animal'}
  
  with open('sampleDictionary.json', 'w') as f:
    json.dump(dict, f)
  
  files.download('sampleDictionary.json')
  f.close()
  </code></pre>
  
  <p>When I try to run this code, it gives this error:</p>
  
  <pre><code>MessageError                              Traceback (most recent call last)
  &lt;ipython-input-29-1251d71a0a36&gt; in &lt;module&gt;()
        7   json.dump(dict, f)
        8 
  ----&gt; 9 files.download('sampleDictionary.json')
       10 f.close()
  
  /usr/local/lib/python3.6/dist-packages/google/colab/files.py in download(filename)
      176       'port': port,
      177       'path': _os.path.abspath(filename),
  --&gt; 178       'name': _os.path.basename(filename),
      179   })
  
  /usr/local/lib/python3.6/dist-packages/google/colab/output/_js.py in eval_js(script, ignore_result)
       37   if ignore_result:
       38     return
  ---&gt; 39   return _message.read_reply_from_input(request_id)
       40 
       41 
  
  /usr/local/lib/python3.6/dist-packages/google/colab/_message.py in read_reply_from_input(message_id, timeout_sec)
      104         reply.get('colab_msg_id') == message_id):
      105       if 'error' in reply:
  --&gt; 106         raise MessageError(reply['error'])
      107       return reply.get('data', None)
      108 
  
  MessageError: TypeError: Failed to fetch
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/GaYVz.png" rel="noreferrer">Click here to see the screenshot of my code and the error</a></p>
  
  <p>Please help me out</p>